On LH as late as possible as there’s never an issue with bin space. But once I’m at the gate, I’ll just board as quickly as possible as sitting on the plane is much nicer that sitting at a packed gate.
On SH with a small backpack I’m not stressed about bin space. In a perfect world, I’d love to bird last and just saunter straight to my seat. But this is very hard to actually pull off. Usually boarding either hasn’t started or they’re just calling group 4 if I get to the gate 20-30 mins before departure. And even if you can time it to be the last on, you’ll still have spend ten minutes in the jet bridge to actually get to your seat. So once I’m there, I’ll usually try and wiggle my way to the front. I know people say they like to spend as little time as possible on the plane, but I find being at my seat reading or looking at cat memes on my phone is infinitely better than standing in the mêlée that spills into the pub at gate A5 or A6.
if I have a rollaboard, I’ll be much more proactive at getting on early, particularly if in row 1. Have to say recently, crew bags and safety equipment has been much less of an issue.