Best resource for complete newb Fiber Network Engineer?

My background. I worked for 5+ years as Tier 1 Technical support for a local Telecom company. Never really did anything beyond layer 3 stuff occasionally.

I went through my local colleges CCNA prep courses, and got a good foundation, though it's been a few years, so I've lost most of that I feel like.

I recently got hired as a fiber core Management technician for a different local Telecom and I've suddenly found myself in the middle of Layer 2 stuff, and a shitton of things I'm not familiar with. Stratum 1 timing, DS3 / STS / OC192's etc. etc.

I found some good Fiber Networking basics videos on the TeamNANOG channel on YouTube; those have been immensely helpful and I largely credit them for getting me this job. Now, besides just time on the job and repetition, what other resources are there out there for me to dive into?

Thank you for reading this.