Timelines and Travel

When the world you're writing in is one you also created, knowing how far it is from Point A to Point B is challenging. You can't just look it up on a map someone else created; the map is yours. Likewise, knowing how long it takes to get from Point A to Point B is difficult for many of the same reasons.
What I've tried to do is just to be consistent. I look at the distance between two places, and I think that's about the same distance as two points in the real world - some amount of miles (because I'm American, so I think in miles). And so I think it will take X amount of time to get to the second place. This not knowing is compounded by mode of transportation. In this world of fantasy, people generally get around by foot or by horse. Sometimes I have to look up how long it takes to travel a certain distance by walking or on horseback.
In my current trilogy, half the world is on the water. So to add to the fun, I have to know how long it takes to sail (the Resani are sailors, not rowers) from one place to another. Or take an educated guess.
Again, my working theory is that, as long as I'm consistent in approximate measurements and approximate timelines, then that as good as I can do.
Just for fun, there's also magic. And using spells, the mages can "bend" distance. It doesn't make travel instantaneous - that feel like cheating - but it does make the distances faster to travel.
At the beginning of the process of writing the Dichotomies trilogy, I made a timelines document. Each main character, where they would go on their journey - which I crafted using the map of the world - and then approximately how long it took to get from place to place. And how long each would be in each place.
Because Kymri, Tyagi, and Hallas have to come together at the end of each book to fulfill the prophecy and bring magic back to humans, those timelines had to end up in the same place at the same time.
Fun!