Startup "expenses" are deducted in the year the business first is active. (You would never deduct 2021 expenses on your 2021 tax return unless the business was active and you filed a schedule C, which you say you won't be doing.). You can deduct up to $5000; if the expenses are more than $5000, you may deduct part and must amortize the rest, according to a formula provided by the IRS. There is no particular time limit on expenses, other than that they must be "ordinary and necessary" for the business, and the IRS might question how necessary an expense is if it occurred a long time ago.
However, equipment is somewhat different. Equipment is depreciated based on either its cost or its current fair market value as of the date it is placed in service, whichever is lower. Suppose you buy a camera now for $5000, but you place it in service for the business on July 1, 2022. If the fair market value of that camera in used condition is only $3000 at the time, then your basis for either expensing or depreciating the camera will be $3000, not the full cost of $5000. This principle applies to any assets that can't be expensed (generally, items costing more than $2500 that have a useful life of more than 1 year) and in your case, could conceivably include computers, video and audio recording equipment, and so on.
For that reason, you may want to hold off buying equipment until the year that you will actually place it in service.
