Just quickly, what's the exact question? You say how will you "be able to BF in the night", to which the answer would be, however you usually bf but I'm guessing that's not what you meant!
Do you mean how long will you be able to continue feeding in the night until it dries up?
If that's it, then it would depend on how many feed you're doing and how strong you supply is. If like me, you went down to one feed, when your supply wasn't huge, IME it was a couple of weeks, tops. Although it came back again briefly and went again.
You need a certain amount of feeds to keep you supply going which will vary I imagine from person to person.