When do you move in with your partner? How long should I wait to talk to him about this?

I think you need to ask yourself if this relationship has any long term legs to it. I am not sure how long you have been seeing this person, but if you two are at the place in your relationship were you know you don't want to see other people and you are spending most of your spare time together, then yes I for sure think it is time to discuss moving in. You can start with drawer space, but I think if you feel this is the right person for you long term, then I think the 24/7 living together is the next step and to me a very vital one. You really, really don't know a person until you have lived with them and witness all their habits and styles. This to me is the ultimate decision making process make or break resolution. I know it sounds very crude, but you would take a car out for a test drive and look under the hood before your purchased it wouldn't you? Then why not see what you are getting yourself into? If it isn't meant to be, then you both with come to that conclusion and no big harm done in the long run!