Is there any way to schedule changing of PPPoE connections at a different time of day?

Good Day, 

I was wondering if there is a way to schedule a PPPoE switch/change for a specific time of day? 

I have two ISPs and we use, ISP A during the day, however they do not zero rate data between 00:00 and 06:00, ISP B does. 

I would like to automatically switch to ISP B from 00:05 to 05:55 and then automatically switch back to ISP A. 

Is this possible?

Or will I have to take a manual approach to this? I have around 800GB of data to push up, but I only have a 1Mbps upload speed, so you can see why I would like to automate this task, as it will take the better part of 6 months (gestimate) to do.

I know this is possible with IPCop, but I have all my firewall rules and internal traffic shaping setup (so the wife and the kids dont watch youtube at 1080p or destroy the first 300GB - see below reasons- with other "bandwidth intensive protocols"). So to either change to IPCop or setup it up infront of the Sophos unit in the network is not really a viable option for me.

Reasons:

ISP A - Uncapped account with a throttling policy of down to 4Mbps @ 300GB, down to 2Mbps @ 350GB and then down to after 400GB 256kbps (yup kb not KB) for the rest of the month. But it is reasonably stable and okay for our general home use, browsing, youtube, email, netflix, etc. 

ISP B is a capped 5GB account with Zero rated Data between 00:00 and 06:00, without any throttling policy. 

Hope I didn't over kill with the info.

Many thanks

Sean