I think 3 to 4 weeks is quite a long time for Ethereum to hit its previous all time high, cause after it crossed $1000 it didn't take up to a day before it climbed up to $1100  after that it still made another high that almost see it broke the previous ATH ,  currently the price is about  $1,200+, so the previous ATH which is $1400 looks achieveable in a few days after the correct that took place today, before the month ends we are definitely going to see Ethereum surpassing the previous ATH.