The majority of my class were 135 guys, and they all did fantastic. Know your limitations/memory items/flows prior to showing up the first day, and you're well ahead of the game. I wouldn't worry about this being your first 121. We all had our first 121 gig, and none of us had 121 prior to it. If the low time guys who teach ground school for 2 years can do it, I'd put more money on a 135 guy who knows how to fly, and is motivated to study.
Sent from my VS988 using Tapatalk