Stepping up an old(er) starter

Had some Ringwood ale yeast slurry saved in the fridge since 11/15.

First step was the thick slurry in a 500 ml starter.  Suppose after I crash and decant that, I’ll be alright to step up to the proper size needed?  OG on the brew will be about 1.041.

Unless I am misunderstanding something I don’t think you would need much of any additional starter. if the slurry is from only 2 months ago it should be fine with that OG.

I was just feeling really uncertain about the viability of that slurry and (because I’m not sure how to go about judging the number of healthy cells after that first step) I thought once more couldn’t hurt.

It was the entire slurry from a batch?  If so, I agree with morticai that you’re probably good to go.