How old is too old?

Bree
Me and my husband have been together for eight years. We have two children one boy and one girl. We have been extremely blessed to have them in our lives and for us to be their parents. I am 26 and my husband is 48. I returned back to school a couple years ago to finish my degree and this October I will be finally graduating. Now we have been TTC for a couple years but have not gotten pregnant. We try and stay positive and say that it is not the right time. We are hoping that when I graduate it will be the right time for us to conceive. By then my husband will be 49. Do you think there is an age limit where men should not have a baby because they might get mistaken as the grandpa instead of the dad?