So... I want to learn to direct feature films so have written a feature and will shoot it.
Assuming I am understanding your post here, that you have no aspirations for this project beyond making it yourself. Seeing it all the way through from A to B by your lonesome, just like like Baron Von F and his beloved creature, sans any Igor's foolhardy enough to follow you into the abyss, I'll rattle off a bit...
So it has to be mentioned that you're going to have 9 billion things to stress and get sorted, even at the smallest scale, if you want to do this with the illusion of good production value. It seems for now, to grasp this, you have boiled it all down into (a)write a screenplay and (b)shoot it. Which is fine for focus, but just be aware 'tis but a couple pieces in the puzzle, if you aren't already.
So these 3 stages you outlined are all kind of one conglomeration. Sadly I don't think it will (should) unfold neatly like this. For example you really should be very conscious of, if not implementing, your stage 3 as you start on your stage 1. If it helps for you to separate/label them great, but really its one phase with all the things going on you described, that could last months, or years if you're exceptionally v̶i̶s̶i̶o̶n̶a̶r̶y̶ ̶a̶n̶d̶ ̶p̶a̶r̶t̶i̶c̶u̶l̶a̶r̶ psycho.
Make sure you are only writing to what you can pull off. Really look at your locations, wardrobes, props and whammy's to make sure they are all doable by you and your resources in your accessible locations. And I don't mean just leave out the explosions and spaceships, I also mean deceptively difficult big budget things like a character crying. Leave out anything that could potentially let people see behind your curtain. Doesn't mean this has to be another godforsaken 2 hour movie of people talking in a coffee shop either, its a time to pull in favors... friends with cool houses, or even just rooms, cars, fur coats etc, let alone a buddy that owns a convenience store... or boat. Write to what you have.
An additional, very powerful OFT MISSED, "phase" you will want to include for determining screenplay shaping and revising is BLOCKING. Take your screenplay once you think its tight (it's not, but when you think it is) and get together with anyone to go through the motions. If it can be your cast, great, If your cast are actors, look out now. But just running lines and blocking shots with a couple friends will reveal so much your mind will be blown, your hand with the red pen in it will cramp within the first hour. Things like "Wait, how can I slurp the goulash if I still have the cigarillo in my mouth?", "If my character is looking out the window across the room then how do I know my manservant hung his Opera coat by the front door in order for me to deliver the line 'Wow you've lost a few pounds, hey wait a second is that Himalayan sea salt on your epaulette?'" or "How do I empty the clip from my Mauser C96 into the bad guy if it's still in my holster around the bed post... in Morgan le Fay's room... on the other side of town."
A word of caution, from experience. I encourage you to be extremely selective with who you choose to take technical (even creative to some extant) direction from. A blowhard fronting is actually far more detrimental to your project than your Great Aunt Juniper telling you she loves your screenplay. Misinformation you catch in the wind and really take to heart and act upon can spiral, derail and just put a serious whooping on your goals. So tread lightly. I got stung myself a few times many many moons ago, shit set me back.
One last thing worth noting. A big, dreaded, piece of the puzzle you may be missing, right inline with your topic, is the Shooting Script. Once you have made your spec as lean and mean as possible (way past spelling, grammar and format now) - with a strong focus on "Screenplay is story optimized for efficiency" -
then- it is time to start on the next hellacious soul sucking endeavor... the Shooting Script. This is your BLUE PRINT to actually make this thing dance about on an illuminated viewing device, and it is an elusive and esoteric craft all unto itself. Without it you are up an amateur creek without a paddle. A paddle that, unlike explosions and crying actresses, you could have made by yourself within your means if you put in the work. And that's a whole 'notha topic.