N 400 - 5 year period start

[nriq]

I got my GC in July 2011. Now I am applying for Citizenship though I became eligible in 2016. I should put the start date of employment as Feb 2012 with my current employer or July 2011 which is my gc date. In fact I am working in this company for 10 years since Jan 2007

[JoeF]

The start date of employment is when you started working for the company, not the GC date, nor 5 years back.

Just follow the instructions, and don't try to make things up because you think it's what they want. They want the truth, not made-up things.