When would the 2018 Chevy Monte Carlo be coming out
Traditionally in the USA, the next model year's new cars are released for public sale sometime in September. That means they have to shut down the factories and retool for the new model year's cars in August.
If you want to custom order a 2018 Monte Carlo from the factory, with all the options that you want built in, probably the latest you can place your order is June or July. If you want to wait until August, you'll probably be told that the model year car that you want is out of production, and you'll have to settle for whatever the dealer has left sitting on his sales lot, OR wait until all the pre-orders for next years Monte Carlo run out and they can slip yours into the schedule.