Tier 2 Application Time & Contract Length while applying

[tzmnc]

Hi

I know that multiple versions of this question has been asked before, so I am sorry for cross posting, but each scenario is slightly different and I would like to be on the safe side. I would be happy if you could briefly help me on the following two questions.

1) I'm a currently a researcher in a university on Tier 2 visa. When I started working on my current job, by March 2013, I was working part time on a student visa. Then I switched to Tier 2, and got it issued/stamped at October 2013. However, I only started working as full-time in December 2013. I should note that I was still a student until May 2014, however I was on Tier 2.

Can you please tell me when I can apply for ILR, in this scenario?

2) While applying, we must still prove that our employer still needs us. As the researchers in the universities are always on temporary contracts, how many months should there be optimally at minimum, till the end of my contract, by the time I apply?

Thanks a lot in advance