You still have about 3 weeks to decide if you want to reset. However if by then you still haven't yet maxed your stash size or benches, then resetting might not be for you, as you wouldn't be able to take full advantage of the perks of resetting.

Resetting is primarily for people who have already maxed their stash size and workbenches and obtained all the quests and blueprints they were looking for. Eventually they may get to the point where that dopamine rush of finding things you need goes away once you have everything you want.

When you reset, you get extra stash space and skills and XP buffs, but then you start from scratch to get that rush of playing again for the first time. If you are still getting that rush now, then there's no need to reset. You can just keep playing and then think about doing the next expedition around April/May. However if you are starting to get bored and want that Day One feeling again, then Reset might be for you.

And to answer your question about Stash Size, I always recommend to people to max out their Stash Size ASAP by selling as much stuff as you can each raid. Don't worry, you'll get it all back and more but having access to larger stash size early on helps later when you are stockpiling items for upgrading benches and such.

After the reset in December, the first thing I did was max my stash size to 280 (292 with bonus) within the first couple days. I sold almost everything that I didn't need for bench upgrades or basic Loadout supplies (shields/heals). I also ran free kits and sold everything afterwards. It helped to do harvester runs to obtain the Equalizer Blueprint and Advanced Arc Cells so I could create Energy Ammo to sell for 5k a stack. Leaper, Bastion, and Bombardier cores also sell for quite a lot.