how many days to complete a 3 tiered wedding cake with fresh flowers?

i always got told it was unhygienic to put fresh flowers on a cake my mum wanted roses on hers but she wasnt allowed and had to have artificial ones!
not sure about other part of question though sorry!

Hi, I’m a baker and when I have to prepare a fondant cake I can make 3 or 4 days ahead, I saved the flowers until the last day and if you use individually small tubes that you can put water in, I don’t now the name but you can put only one flower at the time, and you can put this into the cake and nothing will happen because this tube is plastic. I don’t know what kind of cake do you prepare but the one I make is the Dominican cake, it’s like a pound cake. I hope I can help you, oh, I forget to tell you that it’s also important the filling you put into the cake, because some of them put the cake in bad condition after only one day I think the best way is no putting any filling inside or you should decorate it the day before at night.