+1, totally doable unless you all thumbs.
And I second the idea of playing with the code separately from getting the relays or whatever into the picture.
Doesn't matter which you do first, just do the two parts alone
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get some software printing plausible actions to be taken with the right timing
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rig some relays and see that you can make them click, and that they can control your external components
For timing a simulation, you can always use shorter times, so you don't have to wait around twenty minutes to see that it did work - 1 minute would prove it, and trust me, will still be agonizing enough to sit through as you test. 
then putting them together and you done.
Speaking of simulation, you can do a bunch of progress without any hardware, check out wokwi.com, it is really very convenient for testing little hacks and experimenting.
a7