how much exercise does a 11 week old puppy need

Very little, wouldn't think it's had its jabs yet to go out. Little play sessions with you indoors or the garden to start building a bond between you. Lots of short training sessions all done very informally at this age, that will tire them out more than anything.

You will be surprised what they can learn at 11 weeks, smart dogs the Border Collie! not that I am biased :)

Have fun
Sandra