Adenium like a lot of sun. BUT you did give it enough sun to get it to bloom on your windowsill. So it is up to you. BC can be very rainy and wet. Adenium definitely like to go from wet to just about bone dry, then get watered again. You can keep it indoors where you have more control of water, as your window has proven to be adequately bright to bring it into bloom. Or you can wait a week or so, for it to stay above 8 C at night. But I would wait. 3C is pretty cold for a tropical tree, that you have coaxed into bloom.
Nice job by the way, getting the tree to bloom. Lovely flowers.
Cold and wet are the "kiss of death" for Adenium.
I would keep it indoors to enjoy this current round of flowers, only put it out after this batch of flowers fade.