Looking on the internet deeply has found these results:

in two days is the most popular phrase on the web.

on two days 112,900,000 results on the web	in two days 162,000,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
We're going on two days here. He's been missing going on two days now. In adopting the Markov report, the European Parliament has endorsed a Commission proposal authorising a driving time of 56 hours a week for workers in the road transport sector and a daily driving time of 10 hours on two days in a week. YOU HAD HER ON TWO DAYS AFTER THE GROUP SUICIDE. My Morgan, it turns out, is brilliant for taking one friend to the pub on two days in June.	I got opening statements in two days. But in two days, the board will release the final 10 percent. They could reach us in two days. They can take the Strymon road and be there in two days. He can make this in two days blindfolded. I want it back in two days exactly. Film Festival is in two days. The fourth arrives in two days.

on two days

112,900,000 results on the web

in two days

162,000,000 results on the web

More popular!

We're going on two days here.
He's been missing going on two days now.
In adopting the Markov report, the European Parliament has endorsed a Commission proposal authorising a driving time of 56 hours a week for workers in the road transport sector and a daily driving time of 10 hours on two days in a week.
YOU HAD HER ON TWO DAYS AFTER THE GROUP SUICIDE.
My Morgan, it turns out, is brilliant for taking one friend to the pub on two days in June.