Use broadband before engineer date?

[#1]

I've got my DSL login for my fibre broadband, and have a DSL modem/router sitting around.
Can I plug this in to my phone socket and connect to the internet using my fibre login? Obviously not expecting fibre speeds, but if I can get any sort of connection it'd be perfect.
Thanks

[#2]

You wouldn't be able to as fibre and normal DSL use different technologies. That's why you get a fibre modem when you order PlusNet Fibre.

[#3]

That's not really what I was after. I now have a DSL account with Plusnet (me@plusdsl.net) and my line is already prepared for an ADSL(2+) connection, as I've had many in the past.
I'm wondering if I can connect with my ADSL2+ router over ADSL2+ with my fibre account with PlusNet, or (if I ask nicely enough) can this be enabled in the short term until my connection is activated in a couple of weeks.
Technically, it should be feasible. It's about whether my account allows the PPPoA connection, right?

[#4]

The broadband username is the same, however if your previous ADSL service has been cancelled it's likely the line connections at the exchange were removed. Certainly the routing information to Plusnet will not be present. You could give the Sales Team a call on 0800 432 0200 option 3 to see what is available. It might take 7 days to activate an ADSL service.