Pre Installation of R6700AX WIFi6 router to an older NETGEAR C6300 cable modem

I wish to make the marriage of these two components as easy as possible.  It seems to me that I should turn off the existing wifi router installed in the cable modem before plugging in the new wifi6 router to the old cable modem.  I also want to power off the two wi fi extenders before starting the hardware install. It would also seem appropriate that I should disable DHCP in the new wifi6 router so that the main router assigns and controls the IP addresses.

These actions seem like the right thing to do in advance.  

Comments?

The older cable modem has an upper bandwith of 680mbs, more than enough for two elderly computer lovers, so there's little reason to upgrade it.  I really need the extra coverage of wifi6. Security cameras are a great way of determining the range of your wifi ... Just 5 feet further left and nothing!