Associating colors with days of the week is another well known example, described in the book "Wednesday is Indigo Blue" ( https://en.wikipedia.org/wiki/Wednesday_Is_Indigo_Blue ). You might find it interesting.
I only know about this because I had a friend in middle school who was a synesthete. We thought he was making it up until we gave him a list of (long) random numbers to describe the colors of. We then mixed up the order and gave them to him a week later and he provided consistent descriptions. It was pretty cool actually, I've always been a bit envious.
Thanks for sharing, I've got some reading to do.
I love to read, actually. As far as I know I haven't noticed any difficulty in colors. I can definitely see a word "red" that may have been written in blue color really screwing with me, but maybe not more than it would screw with any other person.
Monday is red, Tuesday and Thursday are green. Wednesday is a light blue, Friday is red (feels a bit warmer, maybe slightly orange than Monday). Saturday is yellow, Sunday is black (I always associated Sunday with church, and either dread of going or formal wear).
I do this with other things too but days of the week are the most obvious and have been with me my whole life (I'm 30 now).
Oh, I guess I do the inner monologue when estimating time. Something like "Lets see... is it 8 minutes? No that's too fast. 12 minutes? Maybe. Let's go with 11". Didn't even consider it as part of the process until your comment.