One or two days; setup dev environment, database connections(local or remote), checkout code, build, start, debug. Start working tickets, features or bugs. Ask for direction when I need it. I usually don't. The truth is in the code, if you ask you just get people's out dated information. But I've working the same stack for > 10 years (Java enterprise).
Learning the domain takes longer of course, but you don't need domain knowledge to fix bugs or put buttons on a page.
Learning the domain takes longer of course, but you don't need domain knowledge to fix bugs or put buttons on a page.