I think it really depends on how much you're wanting to show, not how much he wants to see. If you want to show none, and it's hard to find something that doesn't give any, then wear a T. We don't mind if you wear T's, we get that you don't always NEED to be dressed up.
If you want to show a little and you're having a hard time with a lot of it showing, try asking the store that you're buying your clothes at, what you can do about it. That's what they're for!
I like to see some, don't cover yourself up totally.
Oh my god! I would LOVE to go out on a first date with a girl built like that who showed a bit of cleavage! I was in a restaurant recently and saw what looked like it had to be a couple on a very early date (either date one or date two). She was wearing a lovely V-neck red dress which showed off a gorgeous pair of what had to be DDs to great effect. I totally thought about how much I'd LOVE to be on a date like that!
That up the you. You could look great and be covered considering the size of them.
Some cleavage is fine. Especially if you're big on top because you don't want to look like you're going out of your way to cover yourself completely. I think it really depends on how you would normally dress... even on a first date you should show yourself (so to speak!) for who you are.