The phrase "during the first two days" is correct and usable in written English.
Example sentence: We only had a few hours to finish the project, so we had to work hard during the first two days.
The course smiled at us during the first two days.
Students may sign up for auditions at the Department of Music during the first two days of the semester.
I taught lessons during the first two days and supervised two group projects for the final two days.
The scene was more orderly and without as many gawkers or well-intentioned volunteers as during the first two days.
Twenty-two of the 33 starting spots were filled during the first two days of qualifying last weekend.
Our results suggest both dermal and oral uptake of pesticide formulations, with the former being especially relevant during the first two days after a pesticide application.
An increase of 22% in the biomass concentration in 4 d was registered, and all nutrients were consumed during the first two days.
RAIN HITS AGAIN The L.P.G.A. Tour shortened the NW Arkansas Championship to 18 holes after rain wiped out much of the competition during the first two days.
Rating: 10 José María Olazábal (non-playing captain) OK, so maybe he should not have kept picking Westwood during the first two days.
García said he had been a little cautious during the first two days but had felt more at ease on Saturday.
The more shares a video generates during the first two days after launch, the higher the viral peak and the greater the overall volume of shares.
