Unless you're changing millions then why bother to change up now. Interest lost versus better excahnge rate is tiny in the amounts most mortals are dealing in.
Last time I went it was around 1.45 and I can remember going to Barbados in 1987 (which is linked to the USD) when it got down as low as 1.12 !!!!!
Anything over 2 is brilliant but wait until nearer the time or get a Post office card before you go and load it up with cash and use it like a debit card. The post office rates on cards are tip top