When I am using vials with more peotides than I can use in three months (my comfort level for leaving things refrigerated), I am filling extra pen cartridges and freezing them. When one cartridge runs out, I pull another one from the freezer into a pen in the fridge. The biggest challenge so far has been labeling cartridges. Labels interfere with pen clearance, so I have to use sharpies labels I can easily remove before inserting cartridge into pen. This is my approach to GLP1s, since they seem very durable to freezing and long term storage.
For Tesamorelin I prefer using it all asap without freezing.
I've prefilled and frozen luer lock syringes for botox - I can never use all 100 units in one day. With BAC saline I am not concerned with bacteria. I have sterile luer lock caps on and syringes are stored in zip loc bags. I wouldn't risk it with fixed needle slin pins. BA keeps bacteria from multiplying inside the solution, but there's nothing to keep the fixed needle sterile once it's been used.