First on the rep percentages..
It's easier to to one of two methods, train to muscle failure or train with a couple reps left over by the last set. Training to muscle failure is choosing a weight just heavy enough to finish the sets and reps. If you're doing 4 sets of 10 but can only do 3 sets of 10 and 1 set of 7 this is ok too.. what you do is instead of adding weight just focus on finishing the reps which is technically progressive loading. I would only do this if you're a couple reps short on the last 2 sets however. This is easier than choosing a percentage of weight each week. I do keep an Excel sheet of my lift totals for different reps and sets, as well as a PR sheet with all my personal best lifts to give me an indicator of what weight to start with. Some people have a "starter" week or use a week to start light to make sure the form is good and they can complete the exercise, then they add weight each week. Your strength increases easier starting lighter rather than hopping to the most weight you can do as it becomes more difficult to add weight when you're already struggling and haven't adapted your body yet to increasing each week.
On the workout-
The workout seems fine, everyone has different rep schemes that they adapt to best. When I switch reps each week, personally I like to do each rep scheme for 2 weeks before changing reps so that my body can adapt to it and I can even progressive overload if needed . It is very hard unless you're keeping track of all your numbers to find the perfect weight to use each week for a rep scheme, so I like to do 2 weeks to make sure I get the perfect weight as well before moving on. If I'm only doing one week at a time rather than 2 I also like to keep my sets the same that way my body is only adapting to the changes in reps rather than sets and it's easier to add weight or subtract each week, allowing your body to grow more efficiently. Ive had good results with the following rep scheme:
Week 1: 3x12-15. Pick a weight for each exercise that allows you to complete the given reps and sets to muscle failure
Week 2: 3x8-10 add weight since you're decreasing reps
Week 3: 3x4-6 (or 5x5 or 6x4 or 4x6) Add weight since you're decreasing reps
Week4: 3x8-10. Keep the weight the same as before, the overload will be the extra reps
Week 5: 3x10-12 keep the weight the same as before, the overload will be the extra reps
The above plan uses linear and delineate periodization techniques to build strength and muscle doing both reps and weight increases. It's also easier to increase weight when you go down a rep scheme as well.
You could also make each of these 2 weeks and do the following:
You can change the sets and might get better results since the sets reflect more of the goals of those 2 weeks. This plan still uses linear and delineate periodization and gets you results two different ways.
You could also just do 4-6 week periods where all the reps are the same and you just focus on adding weight each week before changing the reps. Then do a deload week and switch reps and exercises to better suit those reps. For instance, mostly barbell exercises for reps 6 and below where you should have mostly dumbbell and others for 15 reps+, etc
I would advise looking into undulating periodization as well as linear and delineate periodization, etc.. as this can also enhance your workout.
A good rule of thumb when guessing your weight is to use previous rep schemes you've done in the past. When you add reps you subtract a weight increment. When you go down reps you add a weight increment. A weight increment is roughly 5 lbs for dumbbells and 10 lbs for barbells. If you're doing 30 lbs bicep curl for 10 reps, then 15 reps you'll do 25, and for 6 reps you'll do 35.