dougherty suggests that the Nats may go with a 4 man rotation until 5/8 with several off days on the schedule.
https://www.washingtonpost.com/sports/2021/04/19/nationals-rotation-stephen-strasburg/Monday: Ross vs. St. Louis
Tuesday: Corbin vs. St. Louis
Wednesday: Scherzer vs. St. Louis
Thursday: Off
Friday: Fedde at New York Mets
Saturday: Ross at New York Mets
Sunday: Corbin at New York Mets
April 26: Off
April 27: Scherzer vs. Toronto (in Dunedin, Fla.)
April 28: Fedde vs. Toronto (in Dunedin, Fla.)
April 29: Off
April 30: Ross vs. Miami
May 1: Corbin vs. Miami
May 2: Scherzer vs. Miami
May 3: Off
May 4: Fedde vs. Atlanta
May 5: Ross vs. Atlanta
May 6: Corbin vs. Atlanta
May 7: Scherzer at New York Yankees
May 8: Need another starter to keep everyone on regular rest
...
A more likely scenario is that Lester is back before May 8, meaning Scherzer, Corbin, Ross and Fedde could occasionally get an extra day between outings. ...
The lefty threw 49 pitches in three innings of a simulated game Thursday. If he juices that pitch count Tuesday, when a jump is expected, he could be close to rejoining the Nationals. Martinez hopes for him to log five innings and around 85 pitches.