Starter - 3 liter vs 1 plus 2 liter

Ok, so I am not sure I understand the science well enough to understand the best way to handle starters for harvested yeast - particularly older harvests.

If I have a jar of yeast that is say, 8-12 months old and I want to make a starter from that for a batch, how should I proceed? I know the yeast is likely minimally viable but able to be built up.

Is there a big difference between what I would end up with if I pitch that yeast into a 3 liter starter vs a two step starter? Perhaps a 1 liter and then a two liter?

I am trying to figure out if I have enough yeast having gone the 3 liter method this week. It took a full 2.5 days to take off, but then got normal krausen. Thus far I have been alternating between being on and off a stir plate for 8-12 hour segments.

Any insight into this would be appreciated

To add, to your post, can i pose the question on what the rule of thumb is on how long people save their harvested yeast? BTW, Palmer says that stepping up creates more yeast, but i’m a noob in this area.

How much yeast do you have to start with? What is the gravity of the beer?

Even at 8 months you should still have close to 8% viability. At that viability, you could pitch 215ml of thick slurry into a 1.62L starter on a stir plate and come close to approx 193B cells. Or you could pitch 100ml of thick slurry into a .5L stir plate starter and step to a 1L stir plate starter and have close to 200B cells.