What I was thinking is to make it work in this method.
I get the speed of my robot and keep it as a constant in my code, then once I get the first coordinate, that will be the distance from the initial, so I divide the speed by the distance to get the time needed for that movement, and based on that time, I move the robot accordingly. then once it reaches that coordinate,
Sorry to trample on your illusions but that will not work reliably, if at all.
For example how will the robot know it has reached the co-ordinate rather than some other location?
There will be slippage at the wheels so it won't run in the exact direction that you want it to. And as @bms001 said, distance errors will creep in every time there is a change of direction.
You just might get acceptable results for one or two out-and-back journeys but once the route becomes complicated it will get completely lost.
To experience the problem set up a route in your living room with some chairs to mark the corners. Walk the route and count the steps between turns and the note the direction to turn. Then go back to the start and follow the route with your eyes shut and NO peeking. Then imagine how much more difficult it would be for a totally stupid robot.