You will be fine just make sure your chalk marks are straight.
Personally I prefer a wider apron than the X Kilt instructions suggest.
If you want belt loops - assuming you wear a belt- take them to a shoe- repair shop and ask them to attach them for you. If you don't wear a belt, don't bother.
It's far easier to spend a few dollars at the shop than the swearing and broken needles that will result if you try and do it yourself.
(Somewhere in the archives is a post about making a 'hopper' that helps with sewing thick fabric weights)
Remember pictures & have fun!