Hi I'm wedding planner and decorator from Magic Bali. If you want to do DIY and want to prepare it in advance, I think satin or fake flower can be good ...but if you want to have real flower actually you can do it 1-2 days before but you should put in each blossoms into the plastic tube/container that is filled with water (you can ask the flower shop they should know) and keep it not under direct sun light...air con temperature will be the best ... if you looking for blue color flower but you couldn't find it you can make it by simply choosing white dendorium orchid and spray it with flower spray color. it's available in many different colors. but better to spray it few hours before the wedding not few days before. try it...give a test ...good luck....