Get a handle on technical debt ASAP. Scaling up without addressing it will only compound problems down the line. Also, make sure documentation is up-to-date and easily accessible.

Consider setting up a mentoring system. Newer devs can be paired with more experienced ones, and it can be a huge help in ramping everyone up quickly.

Pair programming can really help spread knowledge across the team. Just make sure not to overdo it as it can be exhausting. Mix up the pairs regularly too to avoid sameness.

Yeah, good luck keeping quality high with 20 devs. More cooks in the kitchen = more mess unless you have really solid processes. Hope you’ve got a good plan for onboarding!

Code reviews are a must! Also, consider leveraging feature flags so you can release a feature to a small percentage of users or even just internally before a full release. That way, any bugs found don’t affect the entire user base.

I've been through a couple of scaling phases. Beyond Agile and JIRA, get ready for cultural shifts. Regularly scheduled retrospectives can help catch any friction or bottlenecks before they become significant problems.

Pair programming is cool but isn't it a bit slow?

Definitely invest in automated testing early! It'll save a lot of headaches. Also, make sure your CI/CD pipelines are up to speed so adding new devs doesn’t slow down the team.