Income in foreign currency - clarification

Thank you for answering both previous questions one and two.

I’m still a little confused, so I apologise for restating the questions but it will ensure I completely understand what to do (as the two answers so far slightly conflict)

1. The customer buys credits on a third-party website that they can use for any teacher.
2. The customer books a lesson.
3. I provide a lesson.
4. The customer has up to three days to confirm the lesson took place.
5. When they confirm, I am credited (they refer to it as ‘credits’ rather than money or income) minus a fixed 15%.
6. I then make a ‘credit withdrawal request’ (in USD, for the whole or part balance), which takes up to 30 days, and the only service they allow withdrawals to is payoneer.
7. On receipt of the payment into Payoneer, Payoneer charge a $2 ‘service fee’. There is no invoice - they just deduct this from the incoming sum.
8. Then when I want to withdraw the funds from Payoneer to my french bank account, they charge a 2% fee.
9. 5 days later I receive a sum of money in my french bank account in EUR labelled ‘Payoneer’.

I have no choice regarding currency conversion and the only point at which my USD income is realised as EUR income is when it comes into my French bank account. At this point, numerous fees and charged have been applied.

So my question is, what should I be declaring. And with what conversion rate should I calculate that declaration? We are talking euros of difference each time but as I am starting out in France I want to start using the best method. At the moment, I spend almost as much time accounting for each lesson as giving them - as I need to track not just when the lesson happened, but the time I got paid - and the website doesn’t make that easy.

Sorry for asking again but it’s confusing me.