Ask HN: As the first developer, how to prepare for new ones

I am the first software developer hire for my company and just graduated college - they have been using contracts before. I am trying to produce the best product as fast as possible but my code to be honest is trash. Not DRY, no testing. But I have been reading a lot on having a great infrastructure and how to do code reviews. The bosses have talked about hiring more devs but still, I am worried how to "managed/work" with them. Any tips from your own experience?