I'm trying to picture this.

You have a number of mature trees that are deciduous. They filter the sunlight coming into most of your yard. You've taken out some because you want to grow full sun plants.

You've replanted with trees/shrubs that may reach ten to twenty feet within what, ten years? (They would in zone 9 but may be slower in a cold winter climate.) You've placed them so their present and eventual spring/autumn shadows (the long ones) don't shade your sunny garden.

You have other trees to drop within one to two years.

First consideration would be for the tree feller fellas. Have they enough clear space to drop and process those trees without harming your new plantings?

Second would be the species of sun lovers that you intend to plant. Some will become leggy and quite soft in part shade and be at risk of damage from frost or wind. They might even grow into awkward shapes in the struggle for light.

You could mulch the area you're planning to plant up to keep weed growth in check.

You could also plant it with annuals that don't mind part shade such as Lobelia and Impatiens to keep it under cultivation. And focus on any underplanting you have in mind to compliment your new trees and shrubs.

Short answer: I'd leave the sunny plantings until the trees are down and use the time to track the shading from your new plantings so you can update your initial plans, as well as putting in any foundational work such as access for working paths and soil amending.

Thanks for the reply :). I've taken out several old diseased crab apples that were causing a mess and inviting deer. This left a very large open corner of my yard and the trees/shrubs that I've planted are in the BACK of this new bed (vs the crabapples were in the front). The weeping pussy willows are grafted small trees (6-7 ft tall eventually and slightly smaller right now) not the giant trees most ppl think of and the Viburnum is Soshoni(sp?) which isn't supposed to get as big as the others but regardless it's placed ok. The corner faces South-West and I thought I was good to go bc my house is far enough away to not cause shadows. The problem now that took me by surprise (and also the trees I will be removing) are 200+ ft tall (oaks I think) that are causing the filtered shade that AREN'T NEAR this bed (so tree guys won't damage what I've planted) but still shades the w/their far reaching branches These trees are coming down eventually but we have SO MANY that need cut that we are doing the dangerous trees first. My lot is/was filled w/over grown trees and hasn't been landscaped in decades. I am trying to do it right. I've made beds/paths and I'm working on improving the soil (even though it's actually pretty nice d/t all the organic material left over the yrs by said trees).
Thanks again for the advice. I guess I'll work elsewhere until the trees come down :(

A 200 ft. oak tree - that's an incredibly large tree! Trying to think of something supportive to say, but just wondering why you didn't get a place with a nice sunny spot instead of cutting down these trees to plant flowers? It's your land, of course, but... A tree that big has got to be at least 200 years old. To sacrifice it so you can spend a few years playing with flowers just seems wrong to me. Why are the trees dangerous? Are they diseased? Not trying to berate you, I just don't understand.

But, that stuff aside, don't be too hard on yourself about plant placement. All gardeners move plants around when they realize the placement is not optimal, other things get too big around it, or it gets too big for where it is. Just part of gardening!

Thanks for the support! I do understand what you're saying and how that sounds. I appreciate these old trees and I'm saving many. The problem is that they are grown so close together that they go up 120 ft or more before there's even a branch. It looks like giant poles. Some are rotting at the base and some are leaning (maybe just searching for light) but we've had 3 fall down since we've moved in. Part of my land I'm leaving all old trees and I've made a woodland garden. I did remove small saplings in that area and I'm in the process of replacing them w/a larger variety of hardwood trees for variety. I also removed a ton of barberry, poison ivy, invasives and I'm adding natives. I've had a professional arborist show me which trees should go and which I should save. My house is surrounded by woods on 3 sides. I love the house and the privacy. The lady that lived here before me was in her 80's when she left and she had raised 4children here all alone as a widow. Her husband died soon after moving in. I can see that she didn't have time for landscaping. No point in giving up on a beautiful house :)
I do appreciate the kind words and help!

Ok, thank you, that is something I can get my mind around now. If an arborist says they should go, that's all you need to know.

In general, shrubs and trees can tolerate lower light levels in their youthful stages, and the mid-day hours are the most powerful, so it sounds like your plan is promising. How long ago did you plant the stuff you mentioned in your original post? If they are where you eventually want them, I would leave them alone unless something starts looking really bad. ...which brings me to specify that when I said (above) part of gardening is moving things around, I didn't really mean trees and shrubs. Sorry for not making that clear initially. Once they get going, they're not easy or fun to move and I think you are correct about your initial desire to put them in their permanent homes right away.

Difficult work you are doing with the PI and buckthorn. I hope it begins to resemble the picture in your mind's eye soon. Kudos!!

So I was walking in my yard today under one of these very tall 'oak' trees and I was hit in the head with a flower. After looking around to see if someone was throwing things at me, I realised that the flower came off the tree. I did some googling and now know that some of my 'oaks' are actually tulip trees. The first branches are so high up I can't see the leaves let alone the flowers. My yard is covered in petals though. I think I'm going to spend the next few days figuring out what is actually out in my yard before I have anything else chainsawed. It's amazing how much I just don't know as a newbie gardener and land owner.