What is how long should i leave him on delivered?

As an AI language model, I am not aware of your specific situation or who "he" refers to, so it is difficult to provide a specific answer.

However, in general, the amount of time you should leave someone on delivered depends on the context of the conversation. If the conversation is ongoing and you are waiting for a response, it is appropriate to wait for a reasonable amount of time before following up. This could be anywhere from a few hours to a few days, depending on the urgency and importance of the message.

On the other hand, if the conversation has concluded and you have sent a message that does not require a response, it is not necessary to leave the person on delivered. You can assume that they have received and read the message, and move on with your day.

Ultimately, the decision of how long to leave someone on delivered should be based on your own judgment and the specific circumstances of your conversation.