So, gradually is better in my opinion. One thing to keep in mind, Google AdBot is going to visit each URL that you add, even if it is the same landing page with different query parameters. So, if you were to input 165K urls at once, the adbot is going to be crawling like crazy. This can, in itself, reduce earnings if your servers can't handle the increased load.
Same holds true for MSN Adcenter bot, although it obeys the crawl-delay robots.txt directive.
Gradually, over weeks/months is better from a quality score perspective too I believe. Just make sure you are done many weeks before the next big buying season.