I think everyone has you covered here, in 2022 I picked up my 1st R1250GS, literally hadn't ridden a Bike since 2005 (a K2 GSXR750), I hadn't even had a test ride, just went and bought the thing, when you get on the bike, you are probably going to think 'B-gger me, this is big, what the hell have I done' I did the whole way home from the centre of Norwich, but you just need take your time (don't give a rat's chaff about what others may be thinking when you first get on the bike), just be aware this is a big bike (once moving you'll wonder what the fuss was about, because the weight fall's away), and also, be firm but positive on the brakes when coming to a stop, there is a little thing called the 'GS Wobble', at under 5 Mph, when you are coming to a stop it (the bike) will tell you its time to brake and get your foot down. After a couple of rides, your confidence will be there, and you'll wonder what the fuss was about, just give your self plenty of time at Junctions, and on inclines etc... til your used to the weight and height of the bike.
I am now on a 2024 GS Adventure, love the thing, and don't even notice the size & Weight anymore, but most important piece of advice, always PARK with the Bike pointing uphill/upcamber, you do not want to have to push these bikes up any kind of incline (unless you have someone with you who can help), hope you have a fantastic time picking up your new bike. Enjoy it ...