First, I commend your excitement. However, after years of experience, I have found that those who want to learn will do whatever it takes and those that don’t care choose to fail no matter how hard you work to help them succeed. Therefore, two peices of advice
1. Pick a mastery method that will be available for kids but not put too much extra work on yourself. You will be very disappointed in the few students that actually take you up on the second chance test. Consider going into it – is this true mastery 80% and retake or optional mastery?
2. Better that retesting, our Spanish teacher offers optional study sessions before or after school where students take an alternate version of the test together with the teacher BEFORE the test date. They learn the thinking process and never face the disappointment of a failed test. This way you don’t have to actually grade two test or to wait on retesting students to average grades.

Those sound really good!!! Sometimes when kids do really poorly on one of my tests-like below a 50%-I will let them correct all their answers and type up all their notes to change the grade to a 70% (our lowest D-). I then keep the notes until it’s time for semester exams and then return it to them. That way they don’t loose it and have at least one chapter nicely organized and easy to study from!!! I only let each child do this once or twice a year though, it’s too easy for them to take advantage of this kind of kindness.

Your grading methods don’t sound half bad! I got the sense that you want all students to succeed and that you don’t want to smouther them with deadlines but rather let them work at their own pace because not everyone learns the material at the sametime. I agree with the person who wrote to you about making a different re-take test. That makes sense because what the students would end up doing is memorizing the first test rather than study the material. They do that and they will not learn anything from it.

I too will be a new teacher in about a year, except I am early childhood (prek-3). I know it’s difficult to make all the decisions we will have as new teachers and I am jealous that you have already began to think about how you will be assessing your future students!
Good luck and have fun teaching

you have to use a different test for the re-test, or some will cheat.
if the re-test is the same as the 1st one, then people will come on the 1st exam date only to get the exam papers, do it at home without time limit and copy what they did the 2nd exam date

plus, you should put a limit to how much point you can get back that way
either limit to 2, 5 or 10 points the number of points you can get back or limit the max grade you can get if you take the 2nd exam…

the idea is to give a reason to your students to come on the 1st exam and do their best… And still allow those who did good to get better grades if they want to. A good thing that i’ve seen in my student life was a re-test that couldn’t remove points from the 1st grade. only get more points : an average of both grades or the 1st grade alone, depending on what suits the student better.