changing sponsor under tier2

[D_Torque]

Hey everyone,

So, I finally found an employer who is willing to sponsor me.
Things you need to know to answer my humble questions:
1. I have a notice period of 3 months.
2. The employer wants me to join ASAP..
3. Everything is from a view that I want to join the new job by November 15th, 2015
4. My initial Tier 2 started in Mid February, 2014 ie. I will be eligible for ILR in Feb, 2019

A few questions:
1. What start date shall I request my new employer to put in the COS ?
In mind that I may need to serve the three month notice period.
There is a possibility that I may be able to negotiate it, so what will I do in that scenario.
Can I just join the new job if my current employer gets flexible with the notice ?
2. For ILR I need only 3 years and 6 months.. I will be applying for 5 years visa.
But to save some money on the Health Charges, will it work if I request the employer
to put COS end date to be in April, 2019. I have checked it online and I manage to save £200.
3. I will only hand in my notice after I get the visa which is why I am going for premium application.
I have no visibility over the premium application appointment schedule until I pay the money.
Is there any other way to find this ?

This forum has been amazingly helpful to me in the past and I hope I get some replies.

Thank you all in advance.

[geriatrix]

1. If you will give notice only when you are granted leave under new sponsorship, then your start date in CoS should be at least 3 months from now. If you resign on 12-Aug-15, and need to serve 3 months notice, you cannot join the new employer before 12-Nov-15.
So, decide on a start date accordingly. You cannot work for the new employer before being granted leave under their sponsorship.

2. I believe yes.

3. No.