If you're right in Kirkland and not in a frost pocket.... I say put em out.

Well, if you need to get started with the vegetables you are pretty much forced to put the citrus out. Otherwise, I would wait until May. For the most part the cold period in this climate is November through April.

It's warm enough out that citrus will not be killed, but the real question is, how much of a difference is there between the greenhouse and the outside temps. If it's much warmer inside then your citrus will be very unhappy about being put outside. They won't die, but they may drop leaves and flowers and fruit. When I had citrus in an unheated sun room they went in or out when temps inside and out were roughly equal - that meant out in May, in in October.

But if you need the space, you need the space. They won't die. Even if we get a frost still, that won't kill them.

I moved my 5 citrus trees into an unheated south facing room to acclimate them to cooler night temps and in a two weeks out they go-- leaf drop yes, plant pouting, yes-- but back to growth cycle in no time, on Vashon Island anyway

Just be careful to reintroduce them to full sun slowly so their leaves don't burn. (I put mine out for the first time today -- on a shady part of the deck. If I am not too lazy, I will move them in at night for a week or so. And after a week in the shade I will move them to part sun, then full sun.)