I usually wait until I see some white wax or know it is a sort spell away. 
The timing is usually about three weeks after your first hot day, when the 
queen got to lay full-out and the bees had some income.

Depending on your goals, a whole box of black Pierco, tightly spaced and 
waxed, set on a single that is about to explode and with entrances not 
overly large (no top entrances) will drawn out quickly, assuming you have a 
flow or feed them.

Never put on too much at once.  With foundation, one box will hold all the 
bees which would need three drawn boxes, and heat conservation is essential 
for good results.  You want it hot and crowded in there, without overheating 
them.  You should see bees on every top bar when you lift the lid mid-day. 
Some hives will just not draw comb well, so if I see that, I take the 
foundation away from them and give to to willing colonies.  As the comb 
fills out, they will need more room, so you have to watch daily or at least 
often depending on weather.

Although the combs will be perfect, I would not try to winter a cluster on 
them first winter.  If you winter on them, make sure they are the bottom 
box, with more experienced brood comb up top.

I am speaking from the North and from a professional comb honey producer 
perspective.  Drawing comb is what we do, and I used to draw a thousand 
perfect boxes annually on 300 or so selected colonies, plus produce 
extracted honey on those same colonies.  South is different. 

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