Well, you can tell her that as long as she isn't Baptized™, she will not be accountable to the Elders™ should she wish to do anything that goes against the WTS's "rules". Things like going to college. Having a boyfriend who isn't a JW. Having fun.
Not that you want her to run wild, of course, but just to experience a normal adolescence as much as possible before she decides to "settle down".
You could say that you want her to have an education beyond high school and to have the kind of experiences growing up that you now regret that you missed out on.
They've been saying that "the end" is Right Around The Corner™ for decades now, and they'll still be saying it decades from now too. There's no urgency in her getting Baptized™. JWs will try to pressure her in that direction, even getting her JW friends to start distancing themselves from her. Be there for her and let her know that it is a tactic. Then encourage her to make friends outside the JWs so the snubbing doesn't hurt her too much. Give her as much advance warning about these potential behaviours so that she (a) won't be taken by surprise by them and (b) will grow to trust you and the advice you're giving more than she does what the JWs claim or say to her.
Good luck!