Some yeast questions

I recently made a pale ale that I split a gallon out of my 3.5 gallon batch to test ferment with WLP029. Pack was 1 month old and should have had way more yeast than I needed for a gallon, so I boiled and cooled 1.2L of water with 120g of DME cooled and dropped the remaining yeast in there, making a small starter. I did this all late Wednesday.

I came home Thursday to find vigorous fermentation and high krausen in the 1g jug of pale ale. Erlenmeyer flask with starter didn't seem to have much going on visually (no stir plaate btw, just agitation), but quite a bit of yeast has already settled out. My goal was really just to build up a colony I could use at a later date, so a starter is going to be made from whatever I get from this flask anyway. So my question is, what now? At what point do I crash it, and do I just pour into a sterilized mason jar to store right in the current wort? Secondly, is this now considered 2nd generation even though it hasn't gone through a full fermentation?

 

I'd like to think I'll use it within a month, but it would be nice to have the option to keep it viable longer, even if it meant I had to fire it up as a starter again. I think 4-8 weeks is probably a reasonable target, but with a 5 and an 8 year old my schedule does spiral out of control on occasion.

Not really concerned, just like to know how things work. Also I'm just starting out brewing, and at the moment am pretty interested in yeast, and I think I may be trying a bunch of split batches with multiple yeasts. This would mean I'm going to have a bunch of yeasts on hand that I don't necessarily want to be spending $8 per one gallon batch on, so I may be hanging onto some stuff for longer than a few weeks even if it means keeping them viable by firing up new starters. I'll probably never use a strain long enough for it to be an issue unless I find a "house strain," but was just curious if spinning off starter cultures rather than rinsing post fermentation yeast would delay yeast mutation.