When joining a new team the best way to make an impact is to volunteer for something.
Can I test bugs?
Can I fix some bugs?
Can I review your code?
Can I write some docs?
These are the grunt work tasks.
When Grunt Work doesn’t gets done it manifests into heaping loads of technical debt. Technical debt costs your team in the longrun.
So if you’re looking to make an impact – pick up some grunt work.