Pitching amount question

I washed and saved a batch of Nottingham dried yeast, about 10 oz in a jar. How much of that should I pitch on my next brew day? Also, is that too much yeast for one container? Should I separate it into another jar?

Give it another rinse by letting it separate again and pour off three equal parts of just the yeast. 1 jar (1/3 of the yeast cake) will be good up to 3 weeks into a single batch. Longer than that, build a starter first.

I just tried making a yeast starter from old yeast that I had saved in a gallon jug. Used half in one batch, capped it off and refridgerated it the same day. Made the starter 4 months later and got an infection…had to go by the HBS to get my yeast for brew day.