How long will it take for my babys first tooth to come in?

my lillte boy has just turned 3 months and for the past few days he has been crying lots which is very unusual. also he is drooling like mad and is chomping on his hands and anything he can get hold of. he's had a bit of a temperature which i gave him calpol for and that settled him a bit. i breastfeed and also express so his daddy can feed him occassionally but last night he screamed when the bottle was in his mouth but latched onto my breast straight away and was fine. is he teething and how long until his first tooth pops through.anyone breastfed when their LO has teeth as i want to continue as long as i can.