Smoke Out of the Exhaust

The motor for my car was freshened up two summers ago and then it sat on the engine stand buttoned up and covered up for the last two years. Had the chance to take the car out for its first drive today as we are going through last minute bugs and a "good amount" (can't really define that) of smoke was coming out of the tail pipes. Everyone has said that it is common with a motor that has sat for an extended amount of time. My question is how long should that smoke coming out the exhaust persist before I should start worrying about an issue? Car seems to run fine and the engine runs and sounds great. No knocking or anything out of the ordinary. Would appreciate some thoughts on this issue.