Stepping up a starter from harvested yeast?

OK, so a couple of months ago I successfully harvested 4 jars of yeast following this great procedure. Now I am ready to brew a 10 gallon batch.

Does anyone have any idea how many cells are in each jar?

If I were to use the Mr. Malty pitching rate calculator. What do I use for the viability date. It seems I should used the day the batch was brewed as the viability batch, instead of the original date listed on the smack pack.

Still without knowing how many cells are contained the harvested jars, it is difficult to know how many cells I am starting with regardless of the viability?

Can anyone help me out here? I am going to need to step up my yeast that was harvested on 4/15/10. I have 2 jars of yeast to step up. I am planning on brewing 11 gallons of 1.062 beer. Mr. Malty says I need 2.81 liters of starter. How do I get from 2 jars to 2 liters.

Can someone advise a step up procedure for me. I have a single 2l flask and I use a stir plate. Is it as simple as: make starter as usual, wait for krausen to fall, cold crash, decant, then add this new yeast population to a new wort and repeat the starter process?

Please advise on all. Many thanks!

Hi there, I do not know if my method is preferred, but it works just fine.

make a 1.04ish starter @ 16oz. dump both jars (warmed to room temp) into it. place on stir plate.
next day, step up to 1 liter by adding the necessary 1.04 wort into existing fermenting yeast.
next day, add the rest of the wort needed to get to what Mr. Malty says you need. keep on stir plate.

next day or when krausen looks right, cold crash, decant, pitch

I believe you are safe to step up as much as 10x the volume of yeast you have.

At the level you are talking about, you shouldn't have a problem pitching even one jar into .5-1 liter of a starter. Once fermentation in the starter completes, decant, add another liter, and then once fermentation is complete, repeat so that you have 3 liters worth of yeast. You can do it in fewer steps if you want, but you can only get so much liquid in that flask...