Day 3:
Add 6 tsp (2 T) BF and 2 tsp water
This is going to be very easy and you should be confident. You are literally mixing a little flour with a little water and leaving it in a warm place.
Day 3 in the evening, since I noticed a lot of activity -- my mix already doubled -- that then slowed down, I fed it again.
You can do this the next day if yours is not getting going yet -- remember, it will ferment but the timing varies. You are looking for bubbling and rising, hopefully double, but this may take another day: 4T BF and 8 tsp (2 T + 2 tsp) water.
For all the details, chitchat, and conversation in the comments, go to this post.
Today you should start to see a tiny bit of activity in the form of little bubbles. If you don’t soon, make sure the spot your jar is in is very warm. 78℉ is ideal. Low 80℉s is great. Below 75℉ is too cool.
Note that I recorded what I was doing right there on the jar with a Sharpie. You can also keep a notebook.
At this point you can put a rubber band on your jar, at the level of your just-mixed starter. That way you can see its increase in volume, which should start to take place in the next day or two, if not today!