Schedule C: Start-up expenses

Hi! I started my business in mid-2023. Is it true that any business purchase before the first day of business is considered a start-up expense, including items that would otherwise be considered an expense, such as the cost of ingredients, restaurant licenses, liability insurance, etc for a food business? If so, why would anyone not "take" the deduction? I heard that in some cases it might be wise to not take it or take it at another important junction when you're making money? I may have misunderstood, but are there some cases in which it makes sense not to take the deduction?

 

Relatedly, does an R&D type activity like recipe testing/costing before the first day of business qualify as a startup expense?

 

Thanks!