The short answer is "No." You can start any time. If you really want to use 17 week bills over time, I'd do something similar to what she showed in the video. I'd divvy up my ladder into 4 equal pieces and initially purchase a 4-week, 8-week, 13-week and 17-week the same week. Then as the shorter-term bills mature, roll them into 17-week bills. Then your 17-week bills would mature in 4 weeks, 4 weeks, 5 weeks and 4 weeks. At that point simply buy a new 17-week bill as the oldest one matures.
Personally, I like 26-week bills better, but that's just my preference. There's nothing wrong with going with 17-week bills. Also, I wouldn't try to do Auto-roll even if it's available. The auction schedules are regular and predictable. Just use a calendar reminder.