When i move my left shoulder, my left pectoral muscle hurts. is it probably okay for me wait and see what happens?

Yes, probably OK: Pain in your pectoralis muscle with shoulder motion is most likely from a strain from recent overuse of that muscle ( lifting, bench press, chest flies, etc.). Mild strains should resolve spontaneously with time for rest and muscle recuperation. The pain should generally reduce gradually but steadily in a couple days. Once full painfree motion returns, it is safe to resume normal activities.

Yes: If you lifted somethin heavy or strained your shoulder, it is probably ok to wait few days and see if it gets better.