I believe that fall would be a good time to move the olive and lemon trees. As for the fig tree, I would wait a couple of months until it loses its leaves and goes dormant.

Olive and fig trees are very tough and you'll have no problems moving them. The lemon tree is not so tough but still it can be done successfully provided you get as much of its rootball as you can. If you transplant them in fall the trees will have a few months ahead of them to adjust to their new place and will be ready for spring growth.

Good luck,

Nikitas
Greece