Frame rate is a nebulous thing
First thing to understand: the frame rate is going to be "however many frames the game can manage in the specified time interval." Typically games try to achieve 60 frames per second, though others aim for 30 for one reason or another.
And any given frame may not occur with the exact same time taken as the previous or the next frame. For example, to achieve 60 frames per second, each frame would need to compute and render in 16.666 milliseconds. But if one frame takes 15, and the next two take 17, then...well, your average across those three frames is 16.666, everything's fine.
Fine, except for your "it has to be exactly 80ms" animation, which would be visible for 4.8 frames, not 5 frames, as that would be 83ms: 3ms too long. You're just going to have to live with this. Also, 80ms is really short. I suspect that most people won't even recognize this middle frame unless they actively pay attention to the sprite. Its slow enough to be visible, (ie. below the Flicker Fusion Threshold) but too fast to notice at a glance and react to.
In any case, lets look at this window:
The timeline across the right there is timed out in seconds, so your animation will start and finish in about a second and a half (1440ms).
So, measuring things out, you want your transition points about here: