Your usage would be limited to 250 mb / day. Also, if you choose to recharge with 20 bucks more than once in a day, the free usage would anyway lapse the next day. Its doable, but impractical.
Also, i remember till a few months back was unable to recharge the same day and was told by the retailer that could only recharge after 24 hours.Another time was told by retailer that they dont have the rupees 20 recharge anymore and can be done via sancharhut only
Don't know how it stands now