Applying for Tier 2 extension in advance.

[muzzba]

Hi guys,

This question might have been asked previously and I apologise if I sound ignorant.

I wanted to know how much in advance could I make my visa extension application.

My visa is due for renewal in February, if my sponsor give a COS with start date 01 Feb, can I apply for the extension before that date and when will my visa to start from ? 01 Feb or the date the home office made the decision ?

Thanks