If you have had some ad flagged off 3 times before you decide maybe it needs fixing, you are already deep in the hole. If you got really hard headed about things and the ad was flagged off 5+ times, plan on a bit of a vacation---every ad you post will be more likely to be flagged off.
Craigslist is plagued by spammers. Anything you do that makes you look like a spammer will hurt you. One thing about spammers is they are always in a big butthurt hurry to get their spam ads back up. Hurry, hurry, hurry. So don't do this. In general, craigslist is not a good place to get things done in a hurry. It can work for some things, like a rideshare, but it can be very weak for others, like finding someone to work for free on your play. The longer the shot the longer the time for the right person to see the ad. YOU might need to sell something in a hurry but the buyers could care less. Unless your price says you need to sell right now, it's just another ad to them. Just how it is. On the majority of things, you are NOT in a hurry --not from a readers point of view. So, you have time to figure out what went wrong and fix it.
If you posted in the wrong category or on the wrong site, it is probably safe to repost with your corrections immediately. You are putting your ad in front of people that have not seen it before.
The posting volume on your site in a category matters a lot. If there are only 10 posts a day in some category, you may have to wait many days before reposting if you want your ad to look 'fresh'. If there are hundreds of posts a day in a category, waiting 48 hours will do. Remember every category has 'regular' readers. You need to let them see enough new posts to forget about your ad.