What are the most important things I should do while onboarding in order to quickly get up to speed?

• Talk to people! Follow this algorithm: https://boz.com/articles/career-cold-start
• Get started with some very, very simple task just to land something. e.g. fix a comment, add one more test case to an existing unit test, etc. This just helps you understand the workflow and create some interaction with other team members.
• Ask questions and contrast it with your previous experience. Part of the value of being new is the fact that you can ask why some process exists or question certain assumptions. And if it truly doesn't make sense, you can (gently) nudge the team toward removing or revamping that process. Immediate impact!

You have 7 months of experience -- can you contrast the experience between this job and your previous job?

Congrats on the new job! We have a lot of great resources on onboarding. Here are the main ones to go through:

• A similar question from a new junior engineer at Google - This contains a high-level roadmap of things you should do after starting a new job.
• "What can I do to quickly build my reputation as a junior engineer?" - This relates to your goal of becoming a quality contributor. In a nutshell, you want to get good at writing very high-quality code. This Q&A has links to extremely good PRs you can model yours off of.
• "How can I write great code faster?" - This should be very relevant for you as you're both a newer engineer and working at a startup, which will value raw velocity a lot more than other companies. The biggest way to move the needle at a startup is usually to add more features, which takes a lot of code.

Best of luck with the new job! Keep asking questions into Taro as you get a hold of how things work and what problems you and your team are tackling.