It's always cool to make your own CMS. I once made myself one too, procedural coded.

The thing where I've learned the most from is looking at other CMSs en see how they did things. Once you get your own basic structure of how to do things, you can extend easily.

Yes, ofcourse, it may take a few weeks, but I think it's definitely worth it.

Good luck!

P.S. When i started with the CMS I couldn't even code PHP, only ASP.