Get it dry cleaned and hang it from a high ceiling where it only hangs down. Not in the bag all bunched up, but hanging straight down.
Then as the wedding comes closer you can buy or rent a steamer and freshen it up but filling the steamer with distilled water, so it won't have any minerals in the water, then take the steamer and go underneath the ruffles and gently steam them from so they are fluffy again. It won't hurt for you to do this a couple of times. We do this on the formals in our store and it just works like they were ironed but won't melt the fabric like actual ironing will.
A steam iron WILL melt this fabric. A steam iron help parallel to the fabric to steam it WILL melt this fabric. A clothing steamer is not a hot metal plate that water hits and makes a stream of hot hot hot steam. So it is totally different.
You'll need to buy a nice but not expensive steamer if you want to practice and make sure this works for you.
But if you have it cleaned first that will take out all the deep wrinkles and give you a smoother fabric to start with.