US Immigration from El Salvador

My fiance in El Salvador (he is male, I am female), and he has been very unhappy in his job lately. We are currently awaiting NOA2, hopeful it will come through late May or early June based on the activity lately. He has been at his company for 5 1/2 years, but lately it has been more stress than it's worth. He is wondering if it will have any effect on our interview/process if he quits his job now, possibly has another job for a few months before he can (hopefully) finally move here to the US later this year. I would think that since I am the petitioner and I am the one whose finances they are looking at, it doesn't matter what he does with his job, right? I am good to go, I have been in my career for 7 years and I have savings, so there isn't a question of whether I can support him. I would love for him to be able to move on from this job that's been causing him so much stress! He just doesn't want to do anything to jeopardize our process.

Posting on behalf of a friend. She just received her biometrics reuse notice for her paper N-400 application, but the letter is dated a month ago. Her NoA1was also received about one month after it was dated. Because the online tracking is stuck at the "Case has been received" status, I'm worried that she could miss her naturalization interview or an RFE, or even if she gets it in time ultimately have so little time to effectively plan and schedule. Even though the NoA1 lists her address with apartment number in the body of the letter, the recipient section omits it. Could that be why it gets returned to sender? In my personal experience, whenever I get a letter without an apartment number, the mail carrier matches the recipient name to a list of resident names and correctly delivers it anyway. Basically I'm wondering how common this is or if there is anything she can do to get letters directly without them being RTSed back to USCIS and then correctly forwarded back to her. I searched the forums but a lot of posts are about the initial application package being returned to the applicant and not about USCIS' notices. Thanks!