You can not book a tatkal ticket at 8 am on opening day. Site is unavailable for general public till all tatkal tickets are booked. Even if you go railway ticket counter, the agents touts are there to ensure that you do not get the tatkal confirmed tickets, I wanted to book a ticket for lucknow in raipur garib rath through tatkal but useless by all means. I had to approach a travel agent to reach lucknow.
Tatkal means 250 extra for railways and 250 extra for travel agents. Railways please note. Open tatkal for general public also. Limit bandwidth for travel agents, so that we can access the site.