A question about changing lights

I've been growing under pathetic lights, just to see if I could handle growing. I think I can, so I've got a 400W HPS coming today and was wondering if it would be too much of a sudden shock to put the plants I have under it for the remainder of flowering (they've been on 12/12 for almost 4 weeks, actual flowering for a little over 2). Should I swap it in or start a new one with it and let this first one finish how it started?

start it off a little high above the plants(about 2.5' above), and lower it down daily a few inches until you get to about 12-16". Just keep the heat down and you should be good. Also for the first 60-80hrs of an HPS its light intensity isn't at max yet...there is a small burn in period that it goes through until it gets up to full potential. It's not drastic, but it probably starts off at about 80% of maximum and works its way up.

I'd rep you up for the detailed info, but apparently I need to spread some around, I'll catch you when I can.

Gotchya covered Orithil