I agree that there are a lot of important things you should pay attention to while hiring a Node.js developer so you know for sure you won't have any problem in the future. Node.js developer's responsibilities, skills they should have etc., you need to consider all of this. For example, Node.js developers should be familiar with Agile development methods to follow them during product development. The methodology helps to organize planning, design, and testing during the development lifecycle which greatly simplifies the whole process.
I would highly recommend you to read guides on how to hire Node.js developers before you start the whole process to have a better understanding of what kind of a specialist you want to hire. Lately I've been reading a lot of articles on this subject and came across this incredible guide, check it out: https://www.cleveroad.com/blog/how-to-hire-nodejs-developers