Curious if there’s any advantage to leave the part under vacuum overnight and start flowing resin in the morning, or just let it sit under vacuum for an hour or two, make sure no leaks and then pump.

For small stuff you'll probably be fine if you just get the bag down and wait an hour or so (or 20 minutes) and then shoot your infusion.  For larger or thicker items or those with cores, or material that has been stored unwrapped it will help to debulk it under vacuum - how much depends on the part.  If you have issues with bubbles it is a thing to try.  Heat helps too - not oven hot, but uncomfortable room hot.  It is easier to mitigate minor moisture issues by throttling the vacuum level back (50-75%) after you're done filling the part - vapor pressure keeps moisture liquid and small volume.  This is only a problem if its a problem - in many situations moisture is not the cause of problems.