On Discretionary Leave. claiming public fund will affect ILR

[MK_ALD]

My son entered UK in June 2006 on visit visa and left the UK on August 2006. Later came in October 2006 on Student visa, which expired on Jan 2008. During this period, he has fallen sick and remain in UK. Later this visa was extended till September 2008 as discretionary leave outside immigration rules on medical ground. Again applied for applied for extension of his visa as student, which was rejected on December 2008, although he was attending his M.Sc. classes. Home office advised to submit application on medical ground.
In March 2009 again submitted application on medical ground, which was approved and visa was endorsed with validity till Dec 2012 as “Discretionary Leave”. Before expiry of this visa again we submitted FLR(O). In this application, we made a statement that parent are providing the fund for upkeep of the son. A letter signed by the parent (without UKBA asking for any undertaking) was attached with application. The application was approved and bio-metric card with validity till Nov 2016 is issued. Text written on bio-metric card reads as follow;
Front Side
Residence Permit RC083xxxx
Name ----- Romeo
Valid till ---- UK 25 Nov 2016 Photo
Title of Permit ---- Leave to Remain
Remark ------- Work Permitted

Back side
Date and Place of Birth April 1984, Vadodara, Gujarat
Sex ---- Male
Nationality India
Remark -----
At the bottom computerized numbers including name etc.

Question # 1:- When is the best time to apply for ILR

Question # 2:- He has mental health problem and currently he is living with parents. Parents also acquired British Nationality in 2012. Social services are suggesting him to apply for Personal Independent Payment, Employment Support Allowance and Self Directed Support. All these seems to be public fund.
My question is, by taking these funds, will it affect his application for ILR?
We will extremely obliged for your timely reply.

[Amber]

He can claim public funds and should apply for ILR after 6 years DLR. I sincerely hope his health improves.