My advice - don't. I think I posted almost this exact same thing about a year ago. I remember how it felt to worry. It's such a weird time because everyone that knows you can't stop talking about your weight loss but the people that didn't know you, have no idea and just see you as you are. I felt like I wanted my old, fatter self to go away for good and the way to do that was to have my new bf not know about my weight loss. Which of course, meant that my saggy boobs and flabby skin was just the way I was. Ummm....no...so there was that catch 22. Mostly, I think anytime you're with someone new you have body image issues with them and I would hate for you to be so lost in them that you miss out on a "first" with someone that could be the love of your life. You'll want to think back on that time together and not be thinking about something like that. Honey, if he's doing that with you, he likes you and is attracted to you and will be WAY more concerned about his own performance and finding things on you that he likes and probably won't even notice. And yeah, soft lighting, lingerie - good things.
A year later, I'm still struggling with body image issues, but it's different. Now I feel this immense pressure to keep my thinner self and lose weight (it's all me - not him) because he didn't fall in love with me nor has he ever seen me at my higher weight. I almost wish he had and then I would at least know he'd like that too. We never really do get past it. There's always something to worry and fret about as you go through all of the stages.
But don't make a big confessional out of it. I know it feels like this huge thing to you (as it does all of us that have been through significant weight loss), but to him, he's never seen you any way else and will just go with it happily.
Oh and...have fun!