Are we to many to play a campaign?

This is the first time I play D&D as a DM. Me and some friends have discussed starting a campaign for some time now but we made a miskate, we told to many people to join, in total we are eight, seven plus me, I know it is a lot of people to be playing all at once but now we don't want to kick anybody.

I need your opinion on it, is it viable to have a enjoyable experiece playing that many people? also, we saw the starter set and thougt of buying it but I'm having my douts since is seems that already has everything planed even the characters and everything, I get it is for new player but maybe it fits us better if I create our own capaign knowing we are that many people.