What is the Earliest Source? 9 - Not Eating Before ...

What is the earliest source that prohibits eating or learning or working in the evening before each of the following cases:

A. Evening Q'riat Sh'ma
B. B'diqat Hameitz
C. Hadlaqat Ner Hanukkah
D. Counting S'fira
E. Hearing M'gillah

Note I would expect that there is a different answer for each case.

KT
RRW