I've done about 6 of these monsters.
This is just how I do it.... no right or wrong intended.
basting steps:
1/ I lay out the backing on a hard flat surface (making sure I have extra backing...... due to my table size that surface becomes my hardwood floor for this size quilt.
2/ I tape (yes that awful word) with blue painter's tape the backing to the floor starting in the middle of each side and working to the corners (added bonus, I can mark the exact center w/ a sharpie on the tape)
3/ Repeat steps 1 and 2 with the batting
4/ I center and lay out the top
5/ I pin the top to the batting and the backing just like I taped the backing and batting down (these will not be permanent, they hold it in place while I pin from the center out) Making sure it is centered and stretched as much as I can
6/ using the curved safety pins (and this is why it's on a hard surface) I pin from the center out to the mid-line on each side. Then I repeat that for each quadrant created until I've pinned with them about 4" apart- I have a TON of safety pins.
7/ untape and I hand baste, yes this takes forever, but I don't have a long arm machine and I'm not sure I could keep everything aligned anyway. I usually baste with a curved needle and leave it laying there where it was taped, I only untape the areas i'm working on so everything stays put.
8/ roll the backing around the batting and pin (using the pins we originally placed on the edges of the top) with raw edges hidden to prevent fraying- with as long as it takes me to quilt these this is important
9/ I remove the pins in about a 12" block starting in the center and working out. Then I quilt that block and move on to the next work out in the same way I pinned
I can usually get a king size quilt basted in a couple hours which means it's under painter's tape for probably just under an hour. I make No claims that this is the "right" way to baste this type of quilt, it's just what works for me! Good luck.