Most HP endorsement programs I've seen are usually 1-3hrs ground and 2-5hrs flight. A lot will depend on how fast you pick it up and how often you have been flying in past weeks.
It will also depend on which aircraft you do it in since you will have to be endorsed to operate as PIC. If all your time is in a 172 and you do it in a 182, piece of cake, but if you do it in a Cirrus SR22, it will probably take you 10 hours or longer.