If you miss a day or so - no worries, go at your own pace.
Note; if you see liquid on the top (its called houch), that means its fast acting - you can either slow it down or add flour a little more often. To really feed and build, you add the same amount of flour and water to the starter. But you can add a little flour now and then if you just want to give it a snack.
to slow things down put it in a cooler place - to get it more active , get it warmer.
This is the "challenge" of culturing - just getting to "know" it.
Thanks Chef Cathy. You mention slowing it down - what do you do to slow it down? (I got another day behind).
no worries being behind - go at your own pace.... usually the sourdough will wait for you...
I missed a day b/c the day 2 email went to spam and i forgot about it... though i had my mug w. sourdough sitting on the stove. The top was real hard and dried out, but it looked like i had some bubbles forming. I added more flour and also a little extra water because it had dried out. So i guess i'm a day benind now.