Yes. The opening game of next season will be on Saturday (May 10). No games for anybody on Tuesday (May 6). You will be able to schedule a scrimmage for Thursday (May 8).
Sometime this week when you click on Standings, you will link to your new league. I can't remember whether the new schedule is generated at the same instant, but it will be before Saturday.
If I were cautious, I would set a lineup for my opening league game for the scrimmage, and then check mark it as my default lineup. You could then go ahead and set the lineup for the scrimmage.