My babies all started teething at 3 months, with teeth popping through at 4. Bruce is 5 months and the first one finally emerged, but he has been working on it for 2 months! After 4 kids I have found some sanity savers - I wish I had figured these all out with the first kiddo!
2.) Fold a clean baby washcloth into a square, wet on corner and freeze. Baby loves to chew on frozen section until it thaws.
3.) Teething tablets. I like Hyland's best, but Orajel Naturals work well too. I also found liquid vials from Camilia. Very safe (but always do your own research). Baby knows they work and loves to take them (they dissolve in his mouth). I like these for nighttime waking, since he won't be chewing or playing at that time.