Please, please, I need some urgent advice!!
I have to deliver a wedding cake for 150 people this Saturday. The cake will be filled with different flavours (all buttercream) and will be covered in fondant. As it is a cake with the dreaded Wilton stairs , I cannot store it in the refrigerator at the wedding venue. So, I will have to assemble it in the room where the wedding party takes place much in advance. Will it be a problem if I assemble the cake around 12 o'clock noon while it will only be cut around 10 pm? I will be so grateful to you all if you help me out on this!

No problem I can see. As long as your fillings are not perishable (which seems to be the case) and the room is not hot, your cake will be fine. Make sure to have someone sign a waiver that it was left at the venue in perfect condition. My concern would be, leaving it for so long and not knowing how many people will have access to the area, bumping table, poking it, etc.

Yes it should be fine as long as the room is not too humid. Fondant will seal in the cake moisture, so the cake will stay moist and not dry out. Some people have fondant covered cakes sit out for days (not in a hot climate) and they are fine.

It should be ok. Now like the PP mentioned....have someone sign a waiver and as always take plenty of photos of everything! Every angle of the cake and even the placement of the cake table in the room when you were there. That way you know if someone moved it, I had a bride call and tell me her Cake fell during the reception and I needed to come fix it and she wanted her money back....well girlfriend didn't know how OCD I am so I showed up and saw the cake table had been moved clear across the room and the cake fell over, literally over on its side because they tipped the table!!!!! Ugh damn people! Needless to day, I had photos and she did.not get money back! I did fix the Cake though, because I'm nice LOL

Anyway just CYA girl