The choke is more likely to be needed when it's cold, but depending on many factors it may be needed at other times. When the weather is warm, you can open the choke almost right away, whereas in cold weather you may need to leave the choke on longer.
Another trick to start a bike without using the choke would be to give it a little gas as you engage the electric or kick starter. Us middle-aged and older folks used to do this in cars.
Starting at 1 turn out on the mixture screws is probably fine. Ride the bike a bit to warm it up fully. Start to adjust the mixture screw on one side. Turn it in 1/8 turn and see if you can hear the engine speed change. Look at the tach also. If the speed goes up, turn another 1/8 in the same direction. Do this until the speed drops and return to the position of highest idle. If the idle immediately drops on the first 1/8 turn, then go back to 1 turn out and turn 1/8 out. Keep going until the idle drops and then go back to the position of max idle. Adjust the idle speed back to 1200 and do the same thing on the other side. You may stop there or do another round on each side.
If you can't find a maximum within the range of the screw (ideally between 1/2 to 2.5 turns out or thereabouts), then something is wrong with the jetting or there is another problem (timing, air leak, etc.).