You want 628mm (I believe, the scale length is noted in the kit description on the shop site, be sure to confirm) from the inside of the nut to the high E saddle on the bridge (don't measure to the 12th and then from 12th to the bridge, the fret placement is fine, the overall measurement is more accurate for this), with the intonation adjustment wound most of the way forward. You can wrap tape around the posts to temporarily install them without pushing the inserts in. This is also a good time to check neck alignment by temporarily installing the low and high E tuners and running some ordinary string down to the bridge. Make sure they run with an even gap down each side of the neck and you are all good.
Here's a pic of me doing that on an ES kit (Lying on the bench is better, this one had a really tight neck fit so it could sit in the stand)
Also, just be careful when glueing and clamping, You want to make sure there is enough break angle on the neck. If you clamp too hard on the tang of the neck you can greatly reduce that angle which will cause action problems later. Good contact at the heel is the most important.
You can check the break angle with any straight edge like this with the neck clamped.
Different guitar in that pic, but same principle - you want room to have the bridge posts wound out a bit so the bridge sits up off the body.