What to prioritize? Wake up time, wake windows, or bed time?

I haven’t sleep trained my 15 week old yet, but I’m trying to create a daily sleep routine for him to prepare for sleep training.

I’ve read a few books and sleep training plans and have seen conflicting advice on what part of timing of sleep to keep consistent.

Should I focus on the same wake up time each day, the same bed time each day, or consistent wake windows? I can do two of the three, but one of them will always change depending on how long he naps for during the day.

Any advice? Currently we are trying to wake up at the same time each day and are following consistent wake windows, meaning his bedtime each day varies within an hour and a half depending on when his last nap ends.