In Set(O) form under Tier 2 migrant section, what is "For the period before you were granted leave as a Tier 2 migrant, documents showing that you met the relevant requirements of the immigration rules"

Thank you for your help

When changing the employer on Tier 2 visa there could be a couple of weeks gap in the employment history while waiting for the new Tier 2 visa to be issued. Does this affect the ILR application? Thank you.

To apply under 5-year route with SET(O): if the previous employers do not issue the absence letter, are the passport stamps accepted as the evidence? Thanks

I started a job as a Research Fellow two weeks before my PhD viva took place and it took around two months for my Tier-2 visa to be processed. When we apply under 5-year tier-2 route with SET(O) shall we count the start date as the date the visa granted or the start of the job.