DUI and Probation?

I will be going to my sentenceing for a DUI. The prosecutor agreed to give me first time DUI charges no jail time. (hopefully). What happens after sentenceing? Do i go to the probation office right after? do I have to schedule an appointment? What happens when you see a probation officer for the first time? Do they drug test you then and there? Can you get in trouble if you tested positive even if you wernt on probation when you smoked weed?