Missed contraceptive pill. So, how long?

I am on Minesse and have been taking it for almost a year. It is a 28 pill pack with 24 active pills and 4 placebos. Usually I get my period on the fourth day after taking the last active pill and I start the new pack on the same day. This month however I forgot to buy the new pack on time and I will only be starting it on the fourth or fifth day of my period, making it a total of seven/eight days of not taking the pill. Is it safe to have sex straightaway? Or do I need to wait, and if so, how long? The first doctor I saw, who originally prescribed Minesse, told me to start taking the new pack on the fifth day of my period, but she also told me it was a 21 day pill (whereas in fact it is a 24 day pill), so I wasn't sure (I haven't seen her again since, having moved away from that area).