Approriate visitation schedule for my 15 month old?

My ex and I have agreed that we want joint custody of our 15 month old son, however we do not agree on how the schedule should work! He wants to do a week on, week off type of deal. I completely think that my son should spend frequent amounts of time with his father, but i do not know if he is ready to be away from me for that long and his home that he is used to...or be away from his father that long. I would rather my son have one home he sleeps at and wakes up in regularly, to minimize stress and make him feel more secure (he is also about to transition from being with his stay at home mommy to daycare as well). I do think he should spend overnights with his father, just not that long of a period. Am I in the right to be concerned? What are typical, healthy schedules for a 15 month old? (I am his primary care taker, but he also has a very strong bond with his father)