Glad you found someone you click with Doc.

I hope you two have a wonderful relationship, and that when/if something happens with him, it's all you wanted it to be.
Anyway, were it me, you'd probably want to tell him up front. Some guys will be okay with it with proper accommodation whereas some will not want to. I've swapped stories (read: had stories told to me) from both camps. Ultimately, it depends on the guy...and I would think, if we're being perfectly honest, your...ah, flow, I suppose.

Do forgive the wording.
I think the tampon would probably be a good idea, but that's me speaking as a guy with as little knowledge as one could have, so...grain of salt?

lol I'd think it be best to do whatever is most convenient...easy enough to slip out to the bathroom for a quick "Let me freshen up" sort of thing, I would think.
Anyway, best of luck.

I hope you two have a wonderful relationship and many happy times together.

lol Do forgive my ignorance in some of the finer points of things and my wording if it was blunt. I just figured I could offer some advice for his perspective, is all.
Best of luck, and congrats.
Harley