what is a likely time-stamp for how long it will take for an order of 100 Bitcoins to be filled(I am willing to pay above lowest market value, mind you).
look at mtgoxlive, it will show you exactly what price you would pay for any quantity you wish to buy at the moment: http://mtgoxlive.com/orders
there normally is adequate liquidity to accommodate a 100 btc market order (executed in seconds) without pushing the price up much. you need to start talking multiples of that size before you'ld start pushing the price significantly.
either way, to get the best price be patient and let the sellers come to you. seriously, a month away but all of a sudden then there's a fire and you need the bitcoins asap?
it is too bad there are no options or futures markets for bitcoins just yet.