I did my command course 11 months after joining and I echo the comments above about having time to settle in, know how things work, who to call when etc. I’m now 2 years in to BA and feel much more comfortable than I did after that first year.
I also don’t see SH command going senior anytime soon. In general FO’s seem much more interested in going LH. With the current rate of new cadets, people are being unfrozen from SH to go LH and all that you need is 1500hrs.