New/first bill confusion

[#1]

OK, so I am probably asking something obvious, apologies for this, it seems with every new broadband supplier comes a new way of working things and each is different from the other.
So today I signed up with Plusnet and paid upfront for what I was told in a breakdown was line rental, asdl subscription and the new router. I also signed up for the direct debit so am assuming that every month I'll pay for the line rental and asdl connection.
Only thing is, I'm not connected yet and wont be for another 2-3 weeks- I don't even have a connection date yet!
I am trying to budget this and wanted to know, once I am conntected, does the first direct debit payment come out of my account 30 days after that connection date or am I paying in advance and does it come out 9 or so days later (as it would be anything up to 21 days from now that I get connected if the date given is up to-3 weeks).
If so, I'd have paid in advance for a month where I had no service to use- what happens with that? Why don't they just charge me in advance once I've been connected, not during the 3 month waiting period before they've even decided when they will connect me?!

[#2]

Morning popcorn10,
Welcome to the forums
I can understand why this can be confusing, so don't worry.
You have paid for your first month's service, and we will not charge you again until you have received that first month. So if we say that you go live from two weeks today (I'll contact one of our provisioning experts shortly to get them to place your order for you, so chances are your live date will be the 7th November), then the next bill you receive would be 07/12/2014.
I hope this helps, you should receive an email at some point today saying that your order has been placed.
Matty