My DS had none at 14 months and 4 at 2yo (I was starting to think about panicking!). He now has 18 at 3.5yo, they came at fairly steady intervals between 2 and 3 (and he never had any obvious pain when they were coming through). And he was a fairly normal developer in all other regards.
DD has 8 at 14 months. She is a martyr to her teeth, queen of the dribblers when a new tooth is in the offing. She was walking at 9 months, but otherwise same development as DS.