look man
Google adsense offers a user to choose between two advertising types:
CPC i.e cost per click
in this type of selection, u should remember that.. the higher you bid the more frequenty your ad will be displayed on google's partner sites or you can say adsense user's websites.
you can start from as low as 0.03$ to 100$ !!! per click but a decent bid, in my opinion would be $ 0.1/click to $0.5 per click
the second one is cpm i.e; cost per 1000 impressions
i.e. when your ad is displayed 1000 times on google's partner sites.. your a/c is debited with the amount specified by you ... in this ,, a good bid would be 0.1x1000=10$ or more.. in this ad type also.. the more you bid .. the more your ad will be displayed ..
so choose your ad type wisely..
regarding the amount you specify initially.. i.e.. rs 1000 in your case.. that will exhaust as soon as your bid amount exausts.. i.e.. in cpc if you specified $1 per click the amount will exhaust when ur ad is clicked 1000 times.. this isn't time bound... the same is the case with cpm