There are two water drums in my house whose volumes are in the ratio \(1 : 5\). Every day the smaller drum is filled first and then the same pipe is used to fill the bigger drum. Normally by 1:30 pm the smaller drum would just be full. But today, I returned early and started drawing water manually. I poured one-third into the smaller drum and the rest into the bigger drum. I continued this till the smaller drum was full. Immediately after that, I shifted the pipe into the bigger drum. If today the bigger drum was filled 12 minutes earlier than the normal time, when was the smaller drum full?