I would only take that much K unless under the advice and monitoring of a doctor. It's probably fine, but potassium can kill you.
The problem is that it's not known to be safe for pregnancy, so you have to start it and stop it suddenly at ovulation which is not safe.
Can you drink a coconut water instead? It has 600 mg potassium in it and it's in a form that your body can handle more easily - you can keep drinking it in pregnancy.