If you plan to keep the males and the females together, you need roughly 10 gallons per gecko. I keep a male with 2-3 females in a 20 gallon long with a 12"x12" "upstairs" heated level, though others may only choose to keep a max. of 3 geckos in a set-up like that. If you choose to keep your geckos individually and to just introduce the male to the female for mating then a 10 gallon size minimum (200 sq. feet floor space) for each gecko is necessary.
When I get more Females I plan to house 3 females in a 90Q tub and the male in a 28Q tub. THere should be plenty of room to add the male for a couple of weeks. Good luck