I'm doing a bit of planning, but I don't have my books on me to try and work out how long the Trio were at Shell Cottage before they leave to rob Gringotts. I don't think it's ever stated exactly, but is there a reference to days or weeks or whatnot?

I'm trying to establish a sort of timeline between Malfoy Manor, which was the Easter Holidays, to the Battle of Hogwarts on 2nd of May (well, it starts on the 1st, but hey). There's at least two weeks between the two events as that is how long Neville has been in the Room of Requirement when the Trio turn up. But that's as much as I can work out without having the books on me. Can anyone help?

Sarah x