Start off week 1 as above then weeks 2 and 3 try adding a little more weight and aim for the same reps for example:

Week 1-10kg dumbbell split squat (5kg each)

Week 2-12kg dumbbell split squat (6kg each)

Week 3- 15kg dumbbell split squats 8reps each leg

Take note of your reps and weights. Each week try to increase your weight.

As you increase your weight your reps may reduce this is fine as long as you are