I Used To Be On Metoprolol Tartrate Tablets 50mg. 1/2

I used to be on metoprolol tartrate tablets 50mg. 1/2 morning 1/2 night. I weaned off them a few months ago. My cardiologist originally put me on this dose. As my blood pressure was good I just used to go to my g p for my be checks and stopped seeing the cardiologist. My bp has gone up again so my g p has put me on the same medications only 1/2 in the morning at this stage. I have been on them now for 1 week and my BPay is 151/84. Should I be taking the 1/2 in the morning and 1/2 at night or should I be giving this more time to kick in?