Here are some great threads I found by doing a search in the tags... I don't know, maybe it will help.
There is lots more if you start searching in tags and stickies on DADT and when to tell a prospective partner that you are poly or the like.
Generally it seems to be an established theme that the best time to tell someone you are not monogamous is in your dating profile. As soon as possible is not soon enough. In your dating profile you don't even have to meet the person, if they see you aren't mono then they can decide for themselves what to make of you and if you are worth contacting. Why get involved, fall in love and make plans if you are essentially lying about who you really are... if I were in your shoes I would be telling him right this very second... you are not being truthful. I would be very upset if I found out a partner was not telling me the truth about who they were right from the beginning. I would lose trust before even getting started... Mind you DADT would create that kind of mistrust for me too. I wouldn't be with someone or in a situation where large parts of our lives are secret. I don't need details but I need to know what my partner is doing or I just eventually would feel there is no point in being together. I prefer to bond with my partner, connect on such experiences and build more depth rather than move further and further away from our connection. That has been the experience I have had with DADT anyways.