How rumpled is it?
If you pressed it as you went while you were assembling it, I think you might be able to get by with "blocking" it on a very humid day.
Or barely mist it and "hand press" it on a bed or put a sheet down on a carpet and the top on the sheet.
I had to repress a top with a jillion seams - and I did use sizing/starch on it to make the seams stay put. (I usually avoid starch/sizing like the plague - but it really did help in this instance.) Then if the day is humid or damp - the seams stay pressed.