Once someone moves out, as long as you're in agreement with your estranged spouse, you can date though you may wish to be careful if you have children and custody involved. We've been apart for 3 years and it was about 6 months before I dipped my toe in the dating pool. My ex and I agreed it was fine to see others, but if either became involved in a more serious relationship, to have a discussion with the other as this is a small town and people love to talk.