further leave to remain! where to start!

Hi Everyone!!! I can not believe its been over 2 years since I have moved to the uk. My first spousal visa is up on the 20th of Jan 2020 and I was hoping someone could point me in the right direction for a few things:
1. when is the earliest I can apply? I wanted to do an in person appointment in November or December. is that possible?
2. where is the application to apply?
3. what is the cost at the moment for the visa, nhs and in person appointment?
4. I have a mountain of mail. So I was planning on the following for our post proof is this correct?
a. council tax bill 2017
b. water bill October 2019
c. electric bill April 2019
d. council tax bill 2018
e. bank statement October 2018
f. council tax bill 2019
e. water bill October 2019
all are in our names , I additionally have all of our leases from 2017 to present.

thanks for the help in advance!!!

Edited for dates:

1. The earliest you can apply will depend on what date you actually entered the UK (i.e. the date on the stamp on your visa in your passport). The earliest you can apply is 28 days before you reach 30 months in the UK. From your signature, I see your visa was issued at the end of Feb 2017, and from your previous posts, you arrived in the UK on April 28th 2017?

If so, you will reach 30 months on October 28th 2019, so you can apply for FLR(M) 28 days before that... so, 30th September 2019

2. The application is here: https://www.gov.uk/government/publications/apply-to-extend-stay-in-the-uk-as-a-partner-or-dependent-child-form-flrm

3. Current cost is £1033 plus £1000 IHS.

The application system has completely changed now - you now apply online, upload your documents and then attend a biometrics appointment with UKVI's commercial partner, Sopra Steria. I think you can either book a free appointment, or pay about £125 for a specified day/time appointment, or pay extra for them to scan your documents for you, or pay £800 for a premium appointment, which is supposed to give a 24-hour decision.

4. You only need to cover the last 2 years, so if you're applying at the end of September, you want to cover September/October 2017 to September 2019. You need 1 document in each name every 4 months, from at least 3 different sources.

So, for a September application, you might use documents from:
Sep/Oct 2017
Jan/Feb 2017
May/June 2018
Sep/Oct 2018
Jan/Feb 2018
May/June 2019
(Sep 2019)

thank you so much for that! in term of other documents has that changed much?

So husbands bank slips, contact, letter certifying payslips and payslips
lease agreement(is that enough for this? My husband and I are both on the lease)

anything else?

thank you so much for that! in term of other documents has that changed much?

So husbands bank slips, contact, letter certifying payslips and payslips
lease agreement(is that enough for this? My husband and I are both on the lease)

anything else?

Marriage certificate
Make sure the payslips and bank statements span six FULL months (which may mean providing seven months)
Assuming no children or prior marriages/divorces, that's about it.  There hasn't been any significant change to what's required... just changes to how it's submitted.