First Self Assessment

[SH88]

Hello.
Sorry I’m advance for what is probably a super-dumb series of questions.

I have been creating mobile apps since mid-2016.
I received a few tiny payments totalling less than £200 during that first year.

In 2017, the revenue being generated started to increase significantly, to a point where I was receiving regular, monthly payments.

This lead me to officially registering as a sole-trader in September 2017 as I wanted everything to be legit and above board.

I am now coming to the end of my first official Tax Year based on my registration, so all earnings 06th April 2017 - 05th April 2018 will of course be included in my first years earnings. That’s fine, I think.

My question is, what do I do about the small amount earned during 06th April 2016 - 05th April 2017 when I was just starting out developing apps?

Can I add them to my first years earnings somehow?
Or do I have to back-date a Tax Return and pay a fine?
Or can they be forgotten given how low the earnings actually are and be considered a hobby until I registered as a Sole-Trader?

Originally I was just going to add them to my first years books, but I don’t want to confuse matters down the line.

Thanks for your help everyone.
Have a great day.

[pawncob]

This was made just for you.

http://www.ukbudget.com/newsroom-budget2016/1000-tax-free-allowance-granted-for-small-traders-and-landlords.aspx