Three days is not much time for the koji enzymes to turn the rice starch into sugar... but by day 3 the moto should look a bit more liquid. Here's what a batch of mine looked like after three days:
But by day 5 I did have a lot of activity:
Also, lower temperatures means slower conversion and slower fermentation.
I try to keep the moto at 70 degrees fahrenheit the first couple of days for increased enzyme activity and I leave the yeast on top to pick up oxygen and to provide a metabolic barrier to other beasties.
Then I start stirring it regularly (more oxygen and mix the enzymes around) and then a few days after that I drop it to 60 degrees and (stop stirring) to reduce some of the esters that a more 'overheated' yeast will produce.