State it before checkout
On the product page, in the cart, and in the feed where possible. Buyers who know accept it; buyers who discover it afterwards refund and complain, and both hurt you twice.
It changes your conversion rate, not your eligibility
Expect lower conversion and plan the maths accordingly. That is a margin question, not a compliance one.
Where it becomes a compliance question
When the site implies faster delivery than you provide, or when reviews contradict the stated timeline. That is the misrepresentation finding waiting to happen.