Ah, well it should be fine for now, but alot of unmanaged switches can strip vlan tags this is something to be aware off when you plan to expand your network further in the future and when you want more vlans involved over the switch.
In that case maybe vlans are not needed yet, you can maybe also go for a routed port.
Maybe this can also work?
In that case the only change you need to make for the port assignment is:
go to luci -> network -> interfaces and click on the tab devices.
edit br-lan, and then remove the port you want to be used where the switch is connected on.
then follow the link i sent and where the interface is created make sure the interface has the device selected of the port you previously removed from br-lan.