"Elizabeth: I think that it's bad luck for the groom to see the bride before the wedding.
I don't why I find that interesting..."---Minie Mina
Yeah, the "now is not the time" line isn't an answer to the second (technically third if you count Jack's) proposal. Mina, you may find that line interesting because it's a very "telly" line as opposed to being shown. It is T&T's not-so-subtle way of telling us things are about to go bad. It is meant to be an ominous line that foreshadows all the crap that's about to go down. If you want, you can also assume Elizabeth is a pessimist from it, but there's plenty of evidence to suggest she's not a pessimist.