When to add second brood box with HSC

[Indigo Bee]

I am brand new and started two hives from packages. I wanted to use natural cell size so I put one package in small cell plastic foundation (Pf-120) and the other in HSC. Im using all mediums. My question is how do I know when to add a second medium on the hsc hive? I was thinking that I should wait at least 3 weeks after I see eggs since the package will be dying off until then. A lot of honey is being stored and I see a lot of pollen coming in. Thanx, Tim
P.S. The hive is 9 frame 1 1/4 wide frames in an 8 frame box. All the frames are covered with bees.

[Michael Bush]

A frame being used is what you want to count.  If 8 out of 10 (or 7 out of 8 or so) are being used, then add another box.

[KeyLargoBees]

and for the record.....thats "both sides" being used pretty extensively.....a small patch of drawn comb along the top with the rest of the frame empty doesn't count ;-)

[Indigo Bee]

Thank you both. I was worried that the bees wouldn't like the HSC, but they are putting nectar and pollen in both sides of every frame. No eggs yet, but I saw the queen when she fell on the ground in front of the hive when I removed the includer on day 4. Talk about panic! I picked her up and she walked right into the hive entrance. Tomorrow is day 8 and I will check again for eggs. Thank you Michael for your book. Im using it as my guide.

[Michael Bush]

The queen, in my experience, takes about two weeks to make up her mind to use the HSC.

[Indigo Bee]

Update. I checked my hives on day 8 and found eggs and open brood on the PF-120 frame hive and on the HSC frame hive (About 1 med frame in each). The HSC had a lot more pollen and nectar stores. I'm thinking this is because they didn't need to draw comb. My son pointed out both queens immediately. I am very pleased that the HSC did not seem to be an issue. Actually it looks like it was a boost.  Maybe because of the flow coming in. I noticed a lot of bees on the Pin Oak trees as they are in bloom here. What a great learning time for my son and I. Im hooked for life.