hi there.
I'm no expert but if each light is 40watt. (just a guess) should be fine to get them going.Depending on how many you have.
You should be able to use your mh light pretty soon after that, just give them a chance to spread there first leaves.
When you turn on your mh just make sure there not to close to the top of the plants and you should be fine.
MH produce alot of heat so ventilation is IMPORTANT.
Read all you can about your strain and the basics of growing don't over complicate matters.
Good water ph,good soil,enough light and good ventilation and your on your way.
Nutes are a whole different world Again, don't over do things.
good luck.
someone has nicked my pc to write this this,lol.