Wxman81,
Your picture is a great example of what a tropical Hibiscus R-S looks like during wintering with simple adequate care. The fact that you still receive random blooms is testament to this. I would like to download your image to use as an example for others asking about wintering and leaf loss. That is with your ok.
Looks like you have either a 'Seminole Pink' or 'Painted Lady' cultivar. These are early hybrids that are very resilient. From the picture, I can tell the plant is growing the standard larger leaves on the side facing the window (light source). The leaf loss is very normal as the plant compensates to the changes. You can turn the plant 1/8 a turn every week or so to even out the growth. I winter mine with artificial light for the most part and constantly tweak the environment with the idea of producing a bigger, well balance, high flowering plants each summer.
To answer your question, I would wait a bit longer before pruning. The plant will fill out regardless next year, but the object is more flowers. You are further north and early pruning may develop into long spindly stems before you take them out. Personally I would wait until maybe mid to late March. I will do my heavy spring prune late February to have mine outside in early May.
Things to remember for winter, leaf loss, and pruning in general.
1) Hibiscus R-S loose leaves with environmental changes. This is a natural process. They grow larger leaves in winter and smaller in summer. They also shed leaves regularly like a snake with its skin. The key is watching for patterns.
2) Flowers on H. R-S are formed only on the green stalks and not the bark like stems. Pruning produces more green growth and thus more flowers. During the winter, I do light pruning with the idea of a good prune about 4-6 weeks from putting them out. Since you don't have the artificial lighting like I do your processes will be different.
3) Simple wintering keys will give continued health for the winter and a quicker response this spring. Keep the watering light, but not to the point of bone dry. Also lighten the feeding. H. R-S have a specific nutritional need and these are different in the winter. I use the M-G Violet liquid found in a small bottle during winter. This is a simple 7-7-7 count, and I actually mix in a lower solution than the directions call for. This I add every 2-3 weeks during the winter. I also watch for magnesium or iron deficiencies and lightly add these as needed. When they go outside, I increase the nitrogen and especially the potassium count. The last item I routinely do is give them a bath. Once every 4-6 weeks I give mine a shower. This works multi fold. First it keeps many of the bugs at bay. Next it re-hydrates and plants seem to perk up from it. Lastly, I can flush some of the build ups like salts and excess nutrients.
Hope this helps, and others may have more to add.
Ed

Thanks for the informative and in-depth reply. My only remaining question after reading that, is where on the tree do I prune it?

I will look about 1/3 to 1/2 the way down a branch and find the nodes or bumps on the stem. You will cut just above the node to activate it. And this may perhaps activate the next 2 below it. Remember that the newly activated node(s) will grow in this direction and eventually upwards. This helps in pruning as you can plan how the branch will fill out.
Ed

I will look about 1/3 to 1/2 the way down a branch and find the nodes or bumps on the stem. You will cut just above the node to activate it. And this may perhaps activate the next 2 below it. Remember that the newly activated node(s) will grow in this direction and eventually upwards. This helps in pruning as you can plan how the branch will fill out.
Ed

Hey Ed,

Thanks for all your help. I moved the hibiscus to my home greenhouse to perk it up for spring. Here are some fresh pictures of what it looks like. I'd like to prune it back in the next few days and also do a root pruning as it's completely root bound. I'd like it to look nice and full for spring -- any advice on where to prune?

Wxman81,
I can help, email me directly when you are ready.
Ed

Wxman81,
I can help, email me directly when you are ready.
Ed

If you leave that tie wrap on there, it will grow into the trunk. Buy some green gardening tape and use that instead.

Ed, I just came across this thread and I am in the same boat as wxman. Can I e-mail you as well for some pruning advice?

I have two tree form trop hibiscus that I overwintered in the new greenhouse and I've never done this before. We've had a mild winter here in AL zone 7 and things are already starting to warm up so I would guess it would be safe to start pruning mine but I wasn't quite sure how. Both of mine completely defoliated out in a not-always-heated greenhouse but the plant tissue under the bark still looks green and healthy. I also have a shrub form in a clay pot that continued to bloom during the winter in the same conditions and did not defoliate. I'm used to fiddling with hardy hibsicus in the garden but trop varieties are kinda new to me.

Temps are expected to be in the 50's and 60's for the next week with lows near 40 so I moved them all outside today just in time for the rain that's moving in tonight to give them a bath and a good watering.

Squirrellypete,
Anyone is more than welcome to email me. Often times I add them to my work email as I use it regularly. I thought I might add some pruning sequence photos posted below to help. Most hibiscus are very resilient and enjoy a good prune. Very few CVs like Sea Spray or Black Dragon require a more delicate touch. One item of note is that while they are in dormancy, be careful of the water. Even with well draining soil, root rot can take hold. Mine are inside under extreme dry conditions. I check the leaves twice a day. Once they start to show signs of possible wilting, I give them a small dose of water. I would say that I water about 1 cup of water per foot of height on average. With my potting medium and the low humidity, I water about once a week with most. For me there really is no real chart or table for it...I let the plant dictate and use my gut instinct. Some plants are watered more often than others. Over time you will be able to anticipate their needs.
Hope this helps.
Ed

Below is 2 weeks after a prune. You can see nodes activated and starting to grow new stems.

This prune is after 4 weeks. Notice my once single blooming stem is now broken into several. This will result in 2-3 flower producing stems.
Ed

Lastly, these are prunes made a year ago. Notice the branching. In winter the plants loose a lot of "filler" leaves, so this is a great opportunity to display a photo.
Ed