Fix Python – Get first row value of a given column

This seems like a ridiculously easy question… but I’m not seeing the easy answer I was expecting.
So, how do I get the value at an nth row of a given column in Pandas? (I am particularly interested in the first row, but would be interested in a more general practice as well).
For example, let’s say I want to pull the 1.2 value in Btime as a vari….