Set up for tax purposes this year or next?

Unfortunately, I can't find what I'm looking for on my specific case online, it would be very nice if you could help me. Basically, the question arises to me whether I should start my "small business" (ie sole proprietorship with small business regulation) this year or not until the beginning of next year or whether this shouldn't really matter because of the possibility of loss carryforward or the like?

About the topic:

I have been receiving unemployment benefits for 6 months (the months before that I worked normally as an employee and paid wage tax - approx. 2,500 euro in 2020)

· Earn 650, - € as a trainer (450, - € base + 200, - € ÜL flat rate) which are not counted towards ALG I because I have been doing this for a number of years

· Training costs for this trainer activity this year approx. 1,800 euro

· Laptop, printer bought this year for approx. 800, - € (also necessary for the operation of the business and secondary employment)

Purchases for small business still necessary approx. € 600 (either 2020 or 2021)

The years before I was employed as a normal employee and paid my income tax (excluding small businesses) every year. The small business will stay below € 22,000 in sales next year and I'll be doing my main job again.

How and when do I state this financially most sensibly with the tax, when do I get the rest for the trade or, as said above, is it relatively irrelevant due to the possibility of loss carryforward or the like?

Would be very, very grateful for your short tips.

You have to register your business as soon as you have any intention of making money from it.

The time of registration is irrelevant for "tax purposes".
You are of course only allowed to "work" after registering your business…

You can already claim costs that you have for the business within the framework of anticipated operating expenses. You don't need a business registration for this.

I would advise you too, since it sounds like you've already had expenses for it, otherwise these expire

However, when exactly you start up does not matter from a tax point of view