Sorry for the delayed response. With this amount of lights you will be drawing a total of 187 amps if they were all on at the same time. I calculate the full ballast load which is about 10% more than the lamp wattage. If you run them all at the same time , just make sure the feeder can handle that. If the service is a regular split phase 220v house panel, you would need a 2 pole 125amp minimum just for the lights. If its a 3 phase service, a 3 pole 100amp would do well and it would leave you with more than enough amps for other equipment ( vents, pumps, heaters etc.).
The best way I have found in my experience to control any hid lighting is to first go on ebay and find some used White-Westinghouse size 1 , 3 pole contractors. Each one will handle 3 lights of any wattage you're using. You will need 8 of these ( or if you can't find White-Westinghouse just get another size 1, 3 pole contactor). You will use any timer you like to energize the holding coils of the contactor. The holding coil terminals are usually two small screws located in the center on either side of the contactor. Simply make up an extension cord with a male plug and use the black and white wire on the other end of the cord to terminate onto the holding coil terminals. The male plug end of the cord is plugged into the timer. Turn the timer on and you will hear POP!!! That's a good sign ! That means the holding coil works and it will establish a connection between the three LINE and LOAD terminals located at the top and bottom of the contactor. Now, simply connect your 120 volt hot leg ( usually colored black) to one of the three LOAD terminals on the bottom of the contactor. Also, connect the 120v hot conductor from the ballast supply cord ( which you cut so that you could work with the wire itself and not a plug) to the respective LINE terminal at the top of the contactor. Now splice the white wires from the ballast supply cord and the branch circuit . Also, don't forget to splice the green ground wire to a green grounding conductor from the branch circuit. You can now control 1 light on a timer without frying anything. Simply repeat this process 24 times and remember to only group ballast loads on the same contactor if you intend to have them on simultaneously.