First time business owner. Help!!

Hi!

So not only its my first business in Estonia, but a first enterprise to be opened overall.

I think I already spent hours researching the whole business setup process, but I am scared. I am developing a language school (fully online with AI tutors, and have students already for free, now I want to set up the whole "payments and entity" part. I am bootstrapping it all and I am scared I will run into unexpected expenses, I know there is price for "setting up" and accountant/representative, anything else? any "surprises" I might encounter? Thank you in advance!! I am 19, and as I said it's my first business so I am both very excited and scared!

any help will be very appreciated