How long does it typically take a game to download?

I bought NBA 2k two days ago. Originally, it said it would take a total of 15 hours. No big deal, I went to bed and woke up and it changed to 8 hours. Then yesterday, it jumped up multiple times and now it says it will take 36 hours to download.

I have done speed tests on my internet and there is no abnormality. Haven't had an issue anywhere else, just downloading the game.