When or how often should special journal entries be posted?

For the sake of homework, as a general rule, you will not post any of the "main" columns until all entries have been made. What I mean by that is all the columns that have specific accounts and are not "other." "Other" is for anything that doesn't fit elsewhere, meaning that could be any account. Those can be posted as you do them, or all at the end of the period.

Any subsidiary postings should be done as you go.

In the end, you should follow the instructions given in the problem or by the instructor, or see if the text says something specific about it. Because what I'm saying is just what I see as a general rule.