FLR(M) – "When did you enter the UK?" What date do they want?

I am a British citizen. My American wife’s initial leave to remain in the UK as my spouse was awarded in January 2017 (she transferred from Tier 4) and it expires on 28 July 2019.

We’re going to apply from within the UK for an extension (FLR(M)) next week and we’ll book a UKCVAS appointment as soon as possible after.

As part of the application for an extension, UKVI asks "When did you enter the UK?".

We're not 100% sure what date to put.

My wife visited the UK as a tourist in Winter 2013. We don't think it's this.

My wife entered the UK on a Tier 4 (General) Student Visa in September 2015. We think it might be this.

We met, fell in love and traveled to marry in the US in December 2016. We returned whilst her Tier 4 visa was still valid.

In January 2017 we successfully applied from within the UK for further leave to remain before her tier 4 visa expired.

Her next trip out of the UK and back was in March 2017.

The question "when did you enter the UK?" is frustratingly vague. Can anyone advise what they mean?

I would put the date she arrived here to live in the UK, not to visit... so that would be the date she arrived on her Tier 4 visa in September 2015.

This is what others are saying too. Cheers.