Galah, you are right. So it is his first 3 starts, not 4, that he could get an extra days rest.
So, 4/5 (road), 4/11 (@Mets), 4/17 (Hou), 4/22 (Mia), 4/28 (@LAD), 5/4 (Phi). 5 days rest every time except 4/22, at home, against a division opponent.
This lines up perfectly if 4/16 is a spot start. If it isn't, he may miss Philly at Nats Park.