Work start date- Tier 2 General extension

[RamyaA]

Hi dear valuable members,

My Tier2 General visa is expiring this July 2021. I am trying to apply for an extension in the next month.

* Some one has mentioned that I can apply for extension any time and not just wait for 3 months before the visa expiry date. Can Moderators/senior members confirm this please?

* What work start date should be mentioned in the COS? IHS fee depends on the work start and end dates. Can I mention 15-07-2021 as my work start date even though it is so far from now ?

Visa Start date - 11-09-2011
Visa end date - 14-07-2021

I am a bit confused atm and couldn't understand what to request from my HR.
Any guidance would be very helpful.

Regards
Ramya

[RamyaA]

Sorry, my visa start date was mentioned wrongly in the above post.

Visa Start date - 11-09-2017
Visa end date - 14-07-2021