My point is that I rarely don't regret (for my careers sake) jumping in and delivering (obvious to me heh heh) value right away because I see the code I see where it ought to be and the new boss is really eager to see somethin, but I'm steamrolling toes and throwing elbows in eyes that I was entirely unaware of. I guarantee the people you will work with do not see you as a senior for some time, any misstep is a case against your status,
This is the best advice. And truly senior level people have been around long enough to see a lot of mid-level "senior" developers shoot themselves in the foot. I've also been on a lot of projects where bad practices aren't so bad because the team has strengths in other areas, and also best practices which collapse because the team has other deficiencies holding them back.