If i end my j1 visa earlier and return to my home country,when can i come back to the US with the waiver(tourist visa)?

Your question is a bit unclear. Are you saying that your J1 visa was subject to the two-year foreign residency requirement, and you'd like to eventually re-enter the country on a B-2 tourist visa but without filing a waiver of the 2-year requirement? If so, it's 2 years from the day that you depart the US, even if that day is earlier than the expiration of your visa. Be sure to retain proof of all entries and exits.

There is not specific time frame. You can come back anytime. However, coming soon after you had stayed for a longer period may raise questions whether you come only temporarily for a visit.

You state that you are NOT subject to the two-year home residence rule, correct? If that is true, then what waiver are you talking about? Are you referring to ESTA (visa waiver program)? Please clarify. Best wishes.