Question about EEA Migrant Worker

Hello,

Among all other requirements for eligibility as EEA Migrant Worker, I am having hard time finding what exactly is required for one them.

- Be resident on the first day of academic year (September 1st).

My questions are:

1) If I arrive before September 1st, let's say mid-August, will this satisfy the criteria?
2) If so, what kind of UK residency proof do you require so that you know I arrived before September 1st?
3) Do you accept AirBnb receipt as proof that I was a resident before September 1st?

The receipt would include:

Please let me know what kind of residency proof would be required if I arrived in mid-August prior to September 1st. It is obvious that during that period (about 2 weeks) it is hard to get any utility bills or bank statements from UK banks.