Good Day Mikrotik Engineers

Please would someone with more brain than me guide me down the right path(there must be many of you)

I am attempting to setup my mikrotik with two wan ports as a sort of load balancing setup. However i only want the second port to start routing once my first port is using more than 8mb download.
Is this possible
i imagine i would need to set some queue tree and mangle rules in place but im not sure on what path to take.

Any direction or assistance would be much appreciated.

Bandwidth-based load-balancing with failover. The easy way.
https://mum.mikrotik.com/presentations/US12/tomas.pdf