You don't have to have the proof of funds ready at the time of creating your express entry profile but once you get an ITA, you'll have 3 months to put together the necessary proof so you can submit your application. Once you submit your Express Entry profile, if you have a fairly high Comprehensive Ranking System (CRS) Score, (currently considered to be anything higher than 440 but this could change) you should expect to get your ITA fairly quickly (2 - 3 weeks), and it would therefore behoove you to start arranging the funds and putting together your documentation of it from now.
You don't have to have the proof of funds ready at the time of creating your express entry profile but once you get an ITA, you'll have 3 months to put together the necessary proof so you can submit your application. Once you submit your Express Entry profile, if you have a fairly high Comprehensive Ranking System (CRS) Score, (currently considered to be anything higher than 440 but this could change) you should expect to get your ITA fairly quickly (2 - 3 weeks), and it would therefore behoove you to start arranging the funds and putting together your documentation of it from now.