It is time to start putting your practise to the test and see if you can switch between crotchets and quavers. You need to practise this everyday and really focus in on the metronome pulse. Slow down the BPM if you need to so you can really focus in on the exercise. Increase by 5 bpm as you find yourself accomplishing this speed. Practise at different tempos feeling how the change in pulse can really make the feel of the rhythm change.