If you are using the latest version you can click the Right Mouse Button on the time slider and a very crude beta timeline editor will open, not finished but it's a start
Currently the keyframe-presets represent the camera/target paths as splines in the fractal 3D space,
easing curves are used for all other variables (float uniforms) and
the "time" variable is accessible in the fragment code for use there.
There are an equal number of animation frames between each keyframe, so, to move the camera quickly set the keyframes (F8 key) far apart and to move slowly set them closer together as you are navigating through the fractal. To change one, select it in the "Presets" pull down menu and press the "F9" key, that will highlight (block mark) the keyframe text in the editor, then press "F8" and the selected keyframe preset will be replaced by the current camera/target position.
The easing curves (F7 key) will apply a transition over any number of frames to any currently selected float 1-2-3 or 4 slider component, it will be active in the gui but you must save a preset to use it later. In the preferences dialog you can choose to save easing curve settings in "named" presets (not named keyframe) along with all of the other current uniforms or you can save them in a special preset name "Range-nnnn-nnnn" where nnnn are the start and finish frames, the nnnn part is not interpreted by FragM, they are more for a reminder to the human and could be any alphanumeric characters, the preset prefix name "Range-" is used to tell FragM to save only active easing curve information in this preset. There are some restrictions regarding overlap and using the same variable with a number of different easing curves and you do have to "apply" the "Range-" preset before the easing curves are active.
I hope this helps you understand what is already coded into the program, this is something that needs a lot of work and what is there is mostly proof of concept testing some ideas so it is entirely open for experimenting and could easily be tossed out in favor of something better.