Loose neck pocket on a bought body?

So I've bought all the parts to put together a tele, assuming the neck is aligned with the rest of the guitar properly, does it really matter if the neck pocket is bigger than the heel of the neck? either side of it is about 2 or 3mm away from the neck. Should I put shims in there or will it not make a difference if it's fastened properly?

Except for cosmetics, it doesn't matter if the gap on the sides is 1 mm or 1 meter, a gap is a gap, but 2-3mm would be on the pretty huge side.

As long as the screw holes in the body are the right size (just big enough for the screws to slip through without threading into the wood), it should be perfectly stable.

It's more like 1mm on closer examination. Though when I measure the scale it seems to be closer to 25.75" than 25.5 like it should be. Even with the saddles fully extended... What am I doing wrong?

To get the scale length, you measure from the front edge of the nut to the center of the 12th fret, and multiply that by 2.

The distance from the nut to the center of the saddle will be slightly more than 25.5" but 1/4" is too much.

Does the guitar play in tune up and down the neck?

Ahh ok. In that case it's only an 8th of an inch out. I'll soon find out wether it's too much or not when I get it together. I've only just got the neck on. The rest is all still to assemble. Should have it done today though and will see what happens with the intonation!