For an SDR-AE promotion, you can sometimes get shafted on your comp in Year 1 as they know that most SDR's are desperate to get out of the position and are generally some of the lowest paid people in the sales org.

Depending on your location, whether it’s an SMB or MM position, and if it’s an internal or external promotion, you can expect $120k-$140k for year 1.

Although many people have been promoted to AE
after 6-12 months in my experience that's certainly not the average. I would say 1.5-2 years is the typical time SDR's are promoted internally or even considered for an AE role externally.