I am currently taking Norethisterone. It delays my period by as much as 29 days...and as little as 15 days!As others have said, 2 a day are enough. I get the same length of delay when I take either 2 a day or 3 or day.
My idea is to just insert a sponge before you booking so it is fresh each time. I only see 4 people a day and spread them out that way I feel confident the sponge won’t leak.