Yes, the initial visa granted in December 2015 was granted in the UK, I have been here legally since January 2011, first on Tier 4 student then Tier 2 general. I then got married in 2015 and moved to the 5 yr route.
You can apply no sooner than within 28 days before the start date of your initial spouse visa.
I have been looking around and cannot see anywhere it says the early 28days is applicable to the 5 yr route.
There would have been a paragraph about this in your last approval letter, stating it very clearly. It is also contained in the old paper SET(M) Guidance notes. Note also that the 28 days concession is not an immigration rule, but specifically a concession granted by UKVI to ALL applicants for immigration applications within the UK.
https://webarchive.nationalarchives.gov ... -form-setm
5. When To Apply
You and any children under 18 who are applying with you should apply before the end of your/their permitted stay in the UK when you are nearing completion of the qualifying period required by the Immigration Rules.
Please do not apply more than 28 days before completing that period. If you apply earlier than that, your application may be refused. If that happens, we will not refund the fee and you will have to pay again when reapplying
I am trying to apply at the earliest possible and then for a passport the very next day (because of a potential job opportunity) as my wife is British.
You can't don't qualify for a British passport directly. You have to apply to naturalise as British first, which can take up to 6 months. You are only British, and eligible for a British Passport, AFTER you have been approved and attended your ceremony.
