Gohara threw 62 pitches on 4/17. He should throw ~80 pitches on 4/22 or 4/23, and be ready to pitch in an MLB game as soon as 4/27.
That leaves 2 starts to be filled in by Sims/Wisler/Fried on either 4/19 or 4/20 (depending on when Newk pitches), and again on 4/25. These types of fill in starts are exactly what these AAAA guys are on the roster to do. Gohara should be ready to take over after that.
I think it would be dumb to promote Soroka for 2 starts. The last thing the Braves need is for him to get injured while on a temporary MLB stint, and be stuck on the MLB DL for any amount of time burning his service time. When Soroka comes up it needs to be with the intention of it being permanent.