The standard rule of thumb says birth control is effective after seven days of use or it is effective immediately if you begin it on the first day of your period. I tried to access the information at their website but it was not helpful at all. There should be an information pamphlet with the pills that will answer this question. If you haven't thrown it away, you should read through it.

Seven days is standard waiting time for birth control to be effective. However, if you start taking it during your period you should be safe from then on since it will prevent ovulation. This is also the safest time of the month for sex if you are not on birth control. If you find pills that say to wait a full month I would look into how they work because essentially they should trick the body into thinking its already ovulated which will prevent it from happening, so there shouldn't be a reason this would not happen the first month.