Leaving aside the dramatic needs of Terminator the movie, it seems utterly dumb for Kyle Reese to have to play catch-up to T101, and have to convince Sarah Connor he's out to help her. Even though being shot at may help as motivator, it'd likely have been easier to befriend her earlier way before the attack, and build up a level of trust and rapport.
Is there an in-universe explanation for why Kyle Reese was NOT sent back in time earlier than T101 so he'd have more time to prepare?