My uncle is an SG-1 fanatic and he urged me to start watching Atlantis around the beginning of season 9. He thought I would enjoy them both because some episodes have jokes and cracks that parallel throughout the two shows. I only remember one such moment, but I don’t think it really matters when you start Atlantis.
If you haven’t begun Atlantis yet, I’m very excited for you. Atlantis imo had a better story/plot than SG-1. The only reason why I favor SG-1 over Atlantis is because I enjoyed SG-1’s characters a heck of a lot more. That’s not to say that Atlantis doesn’t have great characters though, because it does.
Oh, also because you just finished the first season of SG-1, I’m double as excited because you have barely scratched the surface for how amazing SG-1 develops. I couldn’t peel my self away from Hulu for like 6 months.