This is the background, from 01 of September 2006 to 28 of February 2012 I lived in UK as student with General student visa. I returned to UK on 01 of July 2013 with a general Tier 2 Visa, since then I have been living here, I got my ILR based on my arrival on 01/Jul/2013
In the citizenship application, there is a question
"When did you first arrive in the UK?"
My question is what date should I use, the date I arrived as Student on 01/Sep/2006 or when i returned to UK with a Tier 2 (01/Jul/2013). In the Nationality Forms guide (April 2019) it says “Enter the day you first arrived with a view to staying in the UK on a long-term basis, and the airport or seaport through which you then entered.”
It is confusing because in the ILR application the question is more straightforward
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.
For the ILR application I used 01/Jul/2013.
I have called three times to the UKBA Citizenship and nationality inquiries, and each time I got a diferent answer from them

I will appreciate your help
Thanks,