Yeast Cake Question

I am running out of the house, and just transferred to a secondary out of my primary, and would like to use it as a starter...

How long can I let it sit in the primary (covered with the lid as we speak), before I have to use it?

I am heading out, and just don't have time to read up and get into getting it out of there at this moment.

My hope is that is ok in there overnight, and I'll prep it tomorrow...

Thanks a bunch

If you leave beer over the top of it and keep it at the same temps you should have till the weekend. I always use mine the same day or next but I think it will last a few days for ya.

It should be good overnight as long as the carboys covered. Prepare and use the yeast as soon as you can for the best possible results.