We can only provide broad statements based on the facts we currently have.
Deciding whether a taxpayer is better off taking the deduction in 2021 or 2022 based on a hypothetical set of facts is not what we currently have with the question. This is not a tax planning matter, we have actual facts. You file the tax return based on those current facts. So I do not agree with @Opus 17 analogy of determining that 2022 may be better regardless of "some definition of starting the business". That is not how the tax laws and tax world operate.
If the taxpayer has begun to function based on the intent of the business, then the business has started. This is regardless of whether the structure is in an LLC or as a sole proprietor. That is not relevant.
The tax courts look to all the facts and circumstances in each case (as does the IRS upon audit). Looking at the regulation 1.248-1(a)(3) it provides "the determination of the date the [corporation] begins business presents a question of fact which must be determined in each case in light of all the circumstances of the particular case". This same "test" is used for section 162 and 195.
The Tax Court ruled in Steven Austin Smith v Commissioner, "...that to function as a going concern means more than just sales...".
The bottom line is that if the original OP truly began business and began to function as a business in 2021, then that is the year the attorney fees would be deductible.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
