Better have it together. If he goes for H-1 and you later want to get H-4, you mostly will have to wait till he has his paystubs. That might take a month or more, as he'll have to have SSN before starting to draw any paychecks.
Its a hassle and you tag along now itself.
If appointment is not available, try to call up the consulate and see if you can attend it as your husband already has an appointment on that day.
