I think people top them around between the 4-5 or the 5-6 node. Cfls dont cause too much strech so I think you could have them at 4 inches and be fine, if streching occurs ( you will see from the first days when they pop out ) then you can put the lights closer btw orange color lights are 2700K, its better for flowering. you should use white "daylight" 6500K for veg... but I grew before with orange without knowing so its ok too. but whites still better
take care!