Hi,
I did a vipasanna retreat years ago, the first for a week then couple of years later for 20 days, Intensive meditation is something that i highly recommend if one never done it before.
for female a week should be okay, for men need at least 3 week or a month. and remember the first 3 days the body still adjusting to the environment , so if you are tempted to quit after a day or two. it's normal reaction. :)
have fun.
Liam
