Excellent candidates can and do find ways to deliver value in their first week and more in their second. Even if it’s demonstrating the ability to learn how the product it deployed and how the team work, that ability to learn quickly and communicate with the team is valuable.
As someone who's worked in over 20 companies as a technical consultant, I mostly agree. However, some companies are better than others at onboarding new engineers. My rule of thumb is to make a meaningful PR within the first week, and do whatever is necessary to make that happen. That sometimes involves bugging the crap out of people with questions, but I try to make up for it with a fast ramp and prodigious output.
Yes, we've had to tweak our on-boarding process for the trial period.
Most candidates have a local dev environment up and running in the first couple of days, and complete their first task (from our real backlog) in the first week. Within the 2-3 week trial period, most are able to finish several meaningful tasks.