I usually recommend a dose of around 2.5 grams (assuming they're dried; fresh shrooms weigh about 10 times as much) for first timers. That should be enough to trip without being an overwhelmingly high dose - although mushroom trips are intense even at low-moderate doses, so don't think that means it'll be a mild experience!
On a relatively empty stomach, most people start coming up in roughly an hour. The come up is pretty fast once it starts and you're usually peaking within another hour. The peak usually lasts around 3-4 hours and then it tapers off for a couple more.
Some basic advice for your first time: make sure you're in a safe and comfortable environment and a good mood; try to have a friend who's not tripping there if possible to keep an eye on you and deal with any situations that arise during your trip (phone calls, knocks at the door, that sort of thing). Don't take them when you're starving, because you won't want to eat for at least the first couple hours, but don't take them right after a big meal either because it'll take much longer to kick in. I usually eat a moderate sized, healthy meal around 3 hours before I dose.
Try to 'go with the flow' and not worry about trying to control the trip or fight the effects. It can be scary, especially your first time; if you start to get anxious, remind yourself that it's just a drug, it'll probably be a lot of fun, and even if it's not it'll be over in a few hours. If that doesn't work, try changing your setting somehow - change the light levels, grab a blanket to curl up in, change the music, go to a different room, things like that. You'll be amazed how much it can help.
If you smoke bud regularly, it combines very well, but it also makes the trip more intense so wait until you're done coming up and you're sure you *want* it to be more intense. If weed makes you super paranoid then I would skip it. If you don't smoke often, you may want to wait till your second trip before trying the combo. Nitrous hits are AMAZING while tripping. Alcohol doesn't combine very well - it kinda dulls the trip.
Check out
Erowid's experience vault for a big collection of trip reports. There's a wide range in the types of experiences people have, and reading a few TRs should give you an idea of that. Psychedelic trips are notoriously difficult to put into words, though, so no matter how many reports you read, I can almost guarantee it won't be exactly what you were expecting.
Good luck, have fun and hopefully in the process you'll learn something about yourself and/or the world you live in!
ohhhh and do you clean them? if so how because these are freshly picked?
