that is a very crude prediction, wkstats takes your average level up time and adds it to your last level up date to get that number. If you take more time than what you do on average (which is likely if you are only on level 5) then it will tell you that you will level up in 0 minutes for quite a bit.
In reality the actual condition for leveling up is passing about 90% of the kanji on the level you are on (the actual number is what’s shown on the wk dashboard).
There’s this userscript, that fills out the predictions page with more actual information, that tells you a better estimate of your level up time based on actual data.