Tier 2 application due to change in employer just before ILR

[ac30]

I just got offered a new job in same role but different employer, still in the shortage occupation list code 2231. I understand that due to change in employer I will have to reapply for a Tier 2 visa. My current BRP is valid until August 2020 and I had only 1 employer since I worked in the UK so all my CoS where from them.

My dilemma is that my 5th year in the UK is 14th November 2019, and I will be eligible to apply for ILR mid-October. I was hoping to take this route so I don't have to pay for the tier 2 + IHS, but I don't know how waiting for the ILR will delay my start date. Will it roughly be the same as when I apply for Tier 2? The new employer expects me to start quite urgently after serving my 8 weeks notice period.

Also, when I do apply for the ILR (I'll take premium service), should I not resign from my current employer yet? And once I do, will they then only start counting 8 weeks notice from there?
If I take the Tier 2 route, will I have problems in the future applying for ILR?

Thanks in advance.

[CR001]

You either need to wait till you have ILR an resign or you need to change visas to your new sponsor and then apply for ILR after a month or two.

You can apply using the super priority service, which should give a decision within 24 hours. You should not be in your notice period though as your current employer is required to give a letter stating that 'you are required in your job at the specified salary for the foreseeable future'.

Your notice period starts from the date you give notice. This has nothing to do with immigration rules.