I have been asked to make the wedding cake for a friend, 2 tier royal iced fruit cake and 100 cup cakes, sponges done and frozen, IMBC strawberry and vanilla done and frozen, fruit cakes made, fed and wrapped, i plan to pipe all cup cakes the day before the wedding, when and how soon can i ice the cake, also should i use glycerin in the royal icing to cover cake? (after marzipan of coarse) and in decoration, either, or. its a pillared cake not stacked any help would be appreciated

No glycerine in any of the royal icing. You need a hard surface even with pillars.

Start icing the cake a week or two before the wedding. Give it one more dose if you can then allow that last dose to mature for 2-3 weeks.

thanks for your advice, wedding in 3 weeks time and i was worried i wouldn't get it all done in time