Family Permit for non-EU parent

[Galanova]

Hello all,

My question is regarding Family permit for a non-EEA mother. I am a British citizen.
For the past 1.5 years I lived in another EU state (Latvia). My mother is financially dependent on me and she received a residence permit in Latvia on the basis of her financial dependency on a EU family member. That means we already proved her financial dependency to the Latvian authorities. I also have a residence permit in Latvia and have other proof that my life centre was transferred to Latvia for 1.5 years (e.g. I got married there, bought a car, lived in the flat belonging to my relative with my husband and mum). Now my husband and I have returned to the UK and would like to apply for my mum’s permit too.
Could you please give your opinions about how strong our case is, considering the above said? If we have already proved my mum’s financial dependency in Latvia, will we have to do the same in the UK or her residence permit will serve as such proof? In Latvia I was self-sufficient (living on my savings) and my husband had a job. Is this enough to prove my financial status in Latvia? I would be very grateful for any information or maybe somebody could share their stories if you had a similar situation.

[Obie]

What is your husband's nationality?

[Galanova]

My husband has dual nationality: Latvian and British

[Galanova]

In regarding to my situation I have already described above, does anybody know the answers to a couple of other questions?
After living in Latvia with us, when we moved back to the UK, my mother went back to Russia at the end of October 2017. We are planning to invite her to live with us again as soon as we sort out our housing situation which will take us a few months.
My question is, does Surinder Singh route allow to apply for the family permit after, say, 6 months of the British citizen returning to the UK? Or do we have to act quicker? While she is living in Russia, do we have to keep track of money transfers to her in order to prove financial dependency?
I tried to find answers to these questions but cannot seem to find a situation which would be similar to ours.
Would be grateful for your opinions.