in(to) the swim (of things)
Actively involved in and knowledgeable about something. It took me a few months to adjust to my new job, but now I'm really into the swim of things. I want to be in the swim when I come back from leave, so I get updates from my team every week.
*in the swim of things
Fig. involved in or participating in events or happenings. (*Typically: be ~; get [into]~.) I've been ill, but soon I'll be back in the swim of things. I can't wait to settle down and get into the swim of things.