« first day (1 day earlier)      last day (19 days later) » 

23:48
Although I also find the referenced answer's argument highly dubious (and it's worth noting that at the time of this statement, the answer has an upvote ratio of less than 75%), there is an argument to be made that a Thief can use a spell scroll as though they could cast the spell (so it automatically works).
I find the following argument more convincing:
1.) The check is called for based on a combination of your class and level.
2.) The thief can ignore both class and level requirements
3.) Therefor, they don't have to make the check.
Although that's open to interpretation, I'll admit that it's an argument I hadn't considered before, and it has merit. (Credit to user @Vigil . I saw this argument in a comment of theirs on this other answer).

« first day (1 day earlier)      last day (19 days later) »