The first return a seasonal preparer works on should not be the first time they see your software, your review notes or this year's law changes. In most firms it is. The new hire arrives the week intake opens, gets a login and a stack of files, and learns by producing review points. The reviewer, who is also the busiest person in the building, does the training one correction at a time.
There is a better order. Train before the season, in a fixed sequence, against a written standard, ...