Nair bikini advice

Never used nair before. I have really thick hair and I'm super prone to ingrowns. Also a poor college student so not looking to dish out for a wax. I'll be in a bikini for three days for a vacation, and I really don't want to deal with shaving irritation and ingrowns.

Should I nair the morning I leave? will it last all three days if it's my first time? Should I nair now and do it again in two weeks before I leave so it doesn't grow in as fast?

I know to do a test spot too. Any advice from nair users appreciated :)