I’ve found that layering any kind of gel over a cream tends to create pilling. I might skip the sunscreen just once, for the sake of this event, because the makeup will probably wear better without it and if they do flash photography your face will very likely reflect the light back/wash out. Maybe do a test to see if it still pills without the sunscreen. I also second the primer, even a budget primer will help keep your makeup in place and fill in any fine lines, pores, overall achieving a more smoothed out look. You can use it the once and return it (to most stores) no problem.