Help on Section 6- Q 6.1 Set (O) form -HSMP+Tier1(G)+Tie1(G)

Hi all,
I have my ILR application in a few days time. While filling in the Set (O) form I need your help in answering Question 6.1 under Immigration History.

My Immigration History:
Came to UK in Sept 2006 - Student Visa
Got IN COUNTRY HSMP visa on: 15 Jan 2008 valid for 2 years
Then Extended 2 Times under Tier1 (G).
(I had to take the 2nd Extension as my days out of UK were over the allowed limit earlier.. Anyhow....thats sorted now...)
My Present Tier1 Visa is valid till Jan 2014.

My ILR application next week is based on:
5 Year eligibility period: 18 November 2008 Till 17 November 2013

Based on the above I am bit confused on how to answer Question 6.1 -

6.1 When did you (the main applicant) first enter the UK? This
refers to the date of your first entry into the UK at the beginning
of the period of stay on which this application is based.

Answer to this:
Should I mention 18 November 2008 OR Should I mention 15 Jan 2008?

I'd really appreciate your help on this.

Many Thanks

Can anyone help on the above query please ..
Awaiting a response..
Thanks

Hi there, I am having a similar situation. Did you find out what the right answer is? Can you please pass on the information?