Is the pot moveable? If so, I'd move it from in front of the window to a more protected spot, and leave it alone for a month or two.

If you do decide to cut it back (which from what I understand of this variety, should not be too big a deal), take cuttings. These should be relatively easy, though this is a bad time of year for cuttings of most perennials like this. Again, if you can move it to a less obvious spot, and wait a month or two for the weather to warm up, and let it start to regenerate on its own, the cuttings you strike then will be better able to root and do well.

BTW, mine sailed through the cold snap we had a few weeks back. It's looking pretty good, though a bit leggy. It will definitely need a hair cut this spring, but I do think its a little early yet. My guess is that the best time to trim would be about the same time for most of the Mediterranean herbs like thyme and lavender, just before they start to really pop new growth. Usually here that's around the end of February, early March.

But then, this is only the second winter I've had mine, and I didn't trim it back last year. Wish I had as it got a little leggier and sprawlier than I would have liked, but them's the breaks. Maybe someone with more direct experience will be able to say more accurately.

Thanks Greenman, your answer is about what I thought but was hoping for something different. Pot is not moveable, it's too big and tied into the irrigation system. It was a real winner this year with the hummingbirds and being as it was in a big pot, the cat couldn't get them. It grew very large and I would have liked it to be covered with flowers instead of just a few at the ends of the branches.

Well, how about a little disguising then? lol... the pots in front of my front door, which had some fall stuff like winter pansies, a fuchsia that was flowering well, some purple leaved kales and such, I basically stuffed the pot full of fir branches after that hard freeze we had knocked most of the stuff flat. The purple kale is actually the only thing looking like much plant wise, though some of the pansies are trying to come back too, and the branches both hide the bare soil and give the plants a little protection. Seems to be working ok, and at the very least, gives you something prettier to look at, lol.

If you do decide to cut it back, let us know how well it does. I'm tempted to start making cuttings of mine as well, for all I said you should wait, lol. Getting impatient... and this is one plant I want to spread around the garden a little more, as the hummers really liked it here, too.