As you start a fresh install, notice that the latest version of vSphere 6.5 introduces a new option that allows to "Install on a new Virtual SAN cluster containing the target host". Proceed with a normal installation.
Select the vCenter option with the embedded PSC.
Select the esxi host that will host the new vCenter appliance.
Name the appliance and provide the root password.
Here is where you see the big difference. Notice the option at the end. Select it.
Name your future datacenter and cluster.
Specify which drives will be used for the Virtual SAN datastore. Indicate which drives will be used for cache and capacity.
The rest is pretty much the same, provide the network related information and continue as usual.
Once the installation is done, the administrator can verify that the vCenter is in working order.
Once the vCenter appliance is running, log in, create the vmkernel port for Virtual SAN on that node and proceed as usual. Add the remaining servers and their vsan ip addresses and you are done.