Birthing class question

Krischelle • Finally pregnant after trying for 9 years! Baby's expected due date: 4/13/2016, five days after our 10 year anniversary!
I am currently 17 weeks and 2 days. This is my first pregnancy. I am thinking about taking a birthing class. I have a supervision high-risk pregnancy so I want to make sure I am taking the necessary and helpful steps. 
How far along were you when you started taking birthing classes and was it helpful? Thanks!