thank you for the reply!

so for example - I started in January 2021. and by April 6th 2021 if my Capital gains isn't above 12.3k. Then I do not need to pay taxes nor fill a form. And this RESETS? (ignoring the past transactions)
 
From April 5th 2021 it be essentially a new year and I got the refreshed allowance of 12.3k for April 5th 2021 - April 6th 2022?
 but yet I will need to hand in the assessment form before January 31st 2022?? but that would ignore jan 2022 - april 2022?? slightly confused, but appreciate any help given.

Or would my first next assessment form will be given after April 6th 2022 and prior to January 31st 2023?

thank you for your time!