yah, in my state, they tell you when you go in for your visit, when your next visit will be.. they usually send you home with an appt card like what you'd get for a dr's appt.. most of the time, they are about a month or so apart..
now, i've been on probation a few times, and the first time, even after i went to rehab and told my po that i was going, he still came to my old house asking to see me and what not as he was in the neighborhood.. so yah, they can and will show up at your house from time to time.. but being that i wasn't home at the time, i don't know what he would have done if i were home..
now the other times i was om proby, they never came out to my crib at all, and nor was i ever given a ua the entire time, but i was also in treatment the whole time and they knew this, so dude really cut me some slack and didn't bust my balls too much..
i agree with fab.. i'm not too sure how heavy you are or how much fat you have, but i'm a big dude, 6 3 or so and weight a good 240, so thc can take over 30 days to get out of my system completely... i'd advise that you just finish smoking this week and not push things too far.. if you want peace of mind, get a home testing kit and piss yourself before you go to proby, that way you're not sweating it out wondering if you passed or failed or what have you..