Problem with 2000 mazda protege.... transmission has to warm up a lot before it starts working. why?

so i checked the fluid.... the amount looks good and its very reddish so i guesss it's fresh... another thing that happens before it warms up is that the overdrive light starts flashing/ blinking... if i drive it while the o/d blinks then the car runs REALLY rough and the gears take such a long time to shift and the gears kick in pretty roughly.... but if it warms up a lot the o/d light stops blinking and the car runs fine for that whole day.... until the next day when it starts all over again....any advice?