The problem with getting to know them first is you're likely to meet many guys who could be relationship-material but won't be endowed enough for your preference. The statistics just aren't in the favor of it and you probably don't feel like you've got enough time to date that many men.
If it was a girl I was meeting and she didn't want me to think her promiscuous, she would need to state it in a way that discourages me escalating on the subject. Something like "By the way, please don't get the wrong idea, but I want to be honest with you and let you know I am only interested in dating someone who's very well endowed. It's not the most important thing to me and doesn't come first before I get to know someone, but I think its only fair I let you know up front."
Make sure its a statement. Don't ask him if he's hung. If he's nervous about it, challenges your statement, or asks you how big, then you can probably assume he's not or he's too insecure for it to be any good anyways.
I love this advice. I have a similar problem to the original poster in that finding a relationship worthy man, who is also size worthy has been extremely challenging for me.
I've tried some different approaches. Sometimes, I've not talked about sex up front and then I start to like someone and then if it gets to the point of sex, I'm often disappointed with size or skill...so the effort was kind of a waste of time. I do meet nice men, but if they can't satisfy me sexually then its not going to work in a relationship. I've also tried Seaside's suggested approach, bringing up sex fairly early on and then backing off until I get to know the person better. It has helped weed out some men who were not a good match for me. For those who know me via this site, know that I do love sex and have been promiscuous. I am selective. I do have my standards, requirements, preferences. I am a sexually open person. I've always loved sex, started young and after separating from my ex I have gone a bit wild...making up for years of not getting what I needed sexually. I've had fun, but the whole random hook up thing gets old.
I was in a marriage that the sex was just average. It was a huge contributor to me being miserable and wanting a divorce. Not the only reason for divorce. I won't settle for ever again...whether it is sex-wise, compatibility-wise, chemistry-wise, personality-wise, or attraction-wise. I need an ideal fit. Some one who fits in my life in and out of my bedroom. I know what I want. I know what I need. I do not expect perfection. I'm not perfect. I have a lot to offer too, other than being a nympho who loves football and beer. But there needs to be a strong foundation to build a relationship on. I don't think its bad to want it all. I do remain optimistic that I'll find the ONE for me.