[quote=@TheUnknowable][@shadowsaint007]I meant time of day.  We want to leave in the morning, then get back just after the attack.[/quote]
[quote=@Letter Bee]It's meant to be some time after midnight; sorry if I wasn't clear.[/quote]
If that's the case, best to roll with the attack, and then go out find the Vault in the morning (or some other time). Leaving in the middle of an Enclave attack is a bit of a chicken move, even if it is business of interest to the Brotherhood.

EDIT: My bad. The attack happens noon the next day, so if we leave at night, we might get some distance before the Enclave strike. If we get back in time, we might actually get to help defend (assuming we don't spend too long at the Vault).