ILR PEO No decision on the day - Letter saying further checks

[needhelp42]

Hi all,
I have applied for ILR (10 yrs route) at Croydon premium service on 26th of September 2017 and I was given a letter stating that the application is valid but further checks will be carried out to get a decision.

I have been in the UK for the past 13 years. To summarise my visa history
Came to the UK in September 2004
1.Sept 2004 – October 2008 – Student visa (4years) and August 2008 – October 2009 Student visa extension (1 year) – Worked part time and did a placement year while I was doing my full time undergrad. All NI and taxes paid.

2.August 2009 – August 2011 – PSW (2 years) and August 2011 - November 2011 Student visa (3 months) – Worked full time and then started studying full time for my masters. While I was studying I did not work. All NI and taxes paid for the period that I worked on my PSW.

3.February 2012 – June 2015 – T1 Entrepreneur (3 years and 4 months) – started my company and worked for a client through my company. Hired 2 employees that worked for me full time for a year. All taxes and NI paid.

4.June 2015 – October 2015 – T2 dependent (4 months) – Switched from T1 Entrepreneur visa to T2 dependent in June 2015, before my T1 Entrepreneur visa expired, which was valid till December 2016. Started working for a company as an employee on PAYE. Did not shut my company. All taxes and NI paid.

5.October 2015 – December 2016 – T2 dependent (1year and 2 months) – My wife changed her job so applied for new T2 dependent. In December 2016 my wife left her job but she still had leave to remain till October 2018 as she did not receive her curtailment letter. At this point I stopped working as an employee and my employer applied for my T2 general visa. The period of December 2016 to Feb 2017 I worked with my employer through my company as contractor from India while they were applying for my visa. All taxes and NI paid.

6.January 2017 – present – T2 General (8 months) – I came back to the UK in January 2017 on T2 General visa which is valid till February 2020 and started working for my employer again. Did not shut my company. All taxes and NI paid.

I did not apply for ILR in 2014 is because I have crossed the 540 days limit and I was covering that up. When I made the application my numbers of days out of the UK were 526 days and I have not been out of the UK for more than 180 days at any given time. I have around 50 entry / exit stamps on my passport.

I thought my application was straight forward as at no given point did I stay in the UK after my Leave to remain had expired. At all times I applied for another visa months before my leave to remain expired. My taxes and NI are up to date and always paid on time.

I would appreciate if someone can suggest what they think the complication might be and how much time do you think they might take to take a decision.