When you need to spend, there is no delay and no other payment method, which is the best time to sell (pay).
Regardless of legal currency or Bitcoin, the needs of people and people are the key, not currency.
That can be a bit hard because you always spend money everyday so it's going to be stressful to decide, I say that if you are on the long-term, you should set a price point that is high that it looks impossible at the current price and then hodl it and only sell it at that point, takes a lot of discipline but you will be able to do it and the results will be astounding for your finances.