World Cup Matched Betting

Hi everyone, maybe a bit of a silly question, but with the WC coming up, is it a good idea to get an oddsmonkey/etc account now and start, or wait until the WC starts properly? I'm worried about missing out on potentially bigger sign up offers the bookies might put out later in the month. From what I've read it also seems like bookies might get suspicious and ban you if they think you're doing matched betting?

100% new to matched betting. Only intending to do the welcome offers to be honest. Any help is appreciated.