FIRST OFF, DON'T BLAME YOURSELF. i know a lot of guys who are insecure like this. they tell their GF all their fantasies, and then as soon as the GF acts on them, the guy freaks out for wahtever reason. this can work both ways, but usually its the guy freaking out. why? Most women see partaking in fantasies as adding a layer of trust, while most guys see it as the woman turning into more of a "Whore". (Agian, most, not ALL on both sides). so while the woman sees it as "Look what I am willing to try!", the guy sees it as "If she acts that way with me, she'd likely be willing to whore around with anyone".
yeah, its silly, but its the reality a lot of guys live in.
as far as a time frame, there is no "Time" to wait really. it varies from person to person. if YOU are the one wanting to try something new and freaky, introduce it slowly to him. mention it during sex, when you are all worked up. if he seems really freaked out by it, just say "it was just talk, I'd never act on it". he'll either be relieved, or curious to try more. if he ISN'T freaked out by it, chances are he is up for it, just didn't know how to bring it up to you.
if HE brings it up, don't seem overly eager to try it! for example, if he mentions bondage, don't run out and buy a super-heavy set of chains and restraints. It will, again, set off his insecurities.
Most guys TALK about fantasies, but less-than-most actually are courageous enough and trusting enough of their woman to act out on them. I am fortunate enough that my wife was receptive to my ideas, and now she comes up with ones on her own. I've never felt threatened by her aggressiveness either.
as far as the closure thing, others have already given you darn good advice, better than I can offer.
good luck, and happy Freaky-ness!