I just started to keep 15g of starter in the fridge, instead of having to feed daily and I'm using it for a recipe for the first time, since storing it in the fridge.

The recipe I'm trying calls for 500g of fed starter, so I took it out of the fridge yesterday, let it come to room temp, and fed it 250g of water and flour, which is almost a 1:17:17 ratio. This was around 1pm yesterday, which is about 19-20 hours ago, and my starter has definitely risen, just not doubled. Maybe about a 33% rise, with bubbles on top. It's sitting on top of a 72 degree seedling mat, also.

Usually, with a 1:1:1 ratio, it would double overnight with no issues, and I know with a much higher ratio it will take longer, but how long should I expect? It doesn't appear to have started falling yet, but I can't see it rising much more. It's clearly active, so is it okay to use, even though it didn't come close to doubling? Should I discard and feed again? I'm hoping I don't have to waste so much flour.

Any help anyone can provide will be greatly appreciated. Thanks in advance!