why did Nehemiah delay a few months in asking the king about returning to Jerusalem?
The king moved around to various territories and among the four different capitals, and perhaps King Artaxerxes was absent for a while. See The Expositors Bible Commentary volume 4 p.684 for more info. Of course, Nehemiah was also praying extensively, and he might have had some reluctance, as the next question discusses. Q: In Neh 1:11 and Neh 2:4, why would someone normally be very reluctant to ask Artaxerxes to rebuild Jerusalem? A: For a century since the return of the exiles, nobody had successfully completed building Jerusalems walls, so why did Nehemiah have the gall to think he would be the one? In addition, Ezra 4:23 shows that Artaxerxes I was the same one who commanded that the building of the walls stop immediately. At this time, Artaxerxes had been king for 20 years, and up to now nobody had told the king that he was in error, or given him any reason to reverse his decree. If Nehemiah had wanted, he could have found all kinds of excuses to not do Gods will and approach the
