When can I put my plant under a HPS lgiht?

I've looked around and read that putting seedlings or too young of plants under such a strong light will kill it. I've had my one plant under two 40 watt CFL long bulbs for about 2 weeks now. It's grown two sets of solid leaves and I can see 4 more starting to sprout. When is it safe to switch from the CFL to my 600 W HPS light and start vegging? Any advice would be greatly appreciated, my first grow here.

if you can put them in the sun with out them wilting your fine if they wilt put them in the shade or back under the cfl

Just make sure you can deal with the heat from the HPS. And technically your plant is probably already vegging.