Small tank

Is it possible for a cycle to last shorter and happen quicker in a twelve gallon?

 

I don't think so. When your ammonia and nitrites are at zero; your nitrates will begin to accumulate. Then they'll spike. This will be followed by a drop-off of nitrates providing the amount of LR is sufficient. When all 3 are at zero, your cycle is done.

In a really big tank the accumulation of the food sources for the bacteria colonies to produce themselves might take longer. If the tank is way smaller, perhaps a shorter time will suffice; but don't count on saving time in cycling because of a small volume of water. Your cycle will be finished within 14 weeks, maybe way before then, but maybe not.

Be patient.