Don't know what the 'proper' advice would be but I keep mine in the greenhouse until they are ready to go out, give them a feed, deadhead regularly and enjoy them!
I am assuming you mean pelargoniums
"The trouble with having an open mind, of course, is that people will insist on coming along and trying to put things in it." Sir Terry Pratchett
My wall basket has overwintered well and the pelargoniums are flowering again. Very pleased as there were some lovely plants in there. I will feed them and count my blessings!
If you overwintered them in a cold greenhouse, they are probably perfectly used to low night temperatures, I would consider them ready to go out. But of course, it depends on your location and weather situation.
Posts
I am assuming you mean pelargoniums
Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.