Artoo and Threepio are captured their first day/night on Tatooine. The Jawas pull up to the Lars’ farm the next day. Artoo goes off to seek Obi Wan that evening. Luke and Threepio don’t start searching for him until early the next day.

Presumably, going into the Jundland Wastes, meeting Obi Wan, destruction of the farm, and heading for Mos Eisley occur on the same day.

The movie doesn’t give any hints how long it takes to get to Alderaan. Probably at least a day, as Han and Chewie have time to chill.

I doubt they were on the Death Star more than a few hours. How long it takes to get to the Yavin system and the time between arrival and the Death Star attack is anyone’s guess. They probably were packing up and fleeing Yavin soon as the medal ceremony was over. Maybe one more day?

TL/DR: A tad less than a week. 😃