I had good results with purchase 180 days. But my LLA are not working at the moment so be careful when testing them.
DataDrivenMarketer
Guest
November 12, 2020 at 9:03 am
You need at least 100 to get an audience going and it will automatically add new people in. So if you have 100 leads and another 50 next month, FB will dynamically update your LLA audiences to match what you are looking for.
I would say 300 events are good to test and maybe use 1-3% LLA-s to test and go broader once you have more events.