wondering how and when to tell him

I'm trying to remember when I told DH. I'm very comfortable with my adoption and open about it so your situation is different. I think I brought it up when we started talking about our respective families. I really don't see a point to bringing it up as a separate topic-unless there's some reason you're concerned about it?

When he makes a remark like "I wonder if we had children would they have freckles like your cousin Estelle?Or "Nearsightedness runs in my family. How about yours?"Or sometime between "Will you marry me?" and "I take this woman."

Like any other deeply personal stuff that you feel reticent in telling new friends/boyfriends, wait until you're ready. If he does ask you family stuff - eg. "how many siblings do you have?" and you would rather talk in general terms, you could say something like: "I come from a very blended family." If he presses you for info, you can just say, "I'll tell you more details another time. It's rather complicated and I'd prefer not to go into it right now." If he keeps pressing you - then just repeat the above sentences. If he STILL pesters you, then emphasise that while you understand his curiousity, you don't want to go into it right now and ask that he respect this. If you do feel comfortable with him, then I'd say just tell him that you're adopted. He'll likely then ask (like many other ignorant non-adoption triangle people), "So have you met your biological family?". Just say whatever you're comfortable in disclosing. Whenever you feel uncomfortable, you can just say my above-mentioned sentences. Only disclose as much as you feel comfortable. IMHO people who press for answers despite one's evasive/vague answers are clueless about the difference between mild curiousity and downright insensitivity/in-your-face nosiness. There's an excellent French film called "Live and Become", where the main character faces the same dilemma and it's handled very well.

I have told all past and present boyfriend's within the first month of "dating." However, I usually hold off on really getting into it for awhile. For example, my boyfriend knew I was adopted almost immediately - I too am very open with it so I imagine it was probably first-date conversation - but I waited about five months to really discuss it with him and show him my non-ID information.

These suggestions sound really good to me. Do it when you're comfortable enough with this person that you feel you can share something that's really personal to you and trust that he will respect its significance to your life.