You don't have to split your dose. In fact, it is usually recommended that you take the whole dose in the morning when you wake up.

I only split my dose because my pain was severe at 3 a.m. I took most (about 2/3) of my dose in the morning at 8 a,m. and 1/3 in the evening at 8 p.m . The smaller evening dose allowed me to sleep all night without pain. A good night of sleep is important. Waking up in pain in the middle of the night wasn't good.

If you aren't having severe pain that wakes you up in the middle of the night, there probably isn't a good reason to spit your dose. If the pain is severe at night you might try the split dose but consult your doctor first.

Your dose can be split in any proportion---whatever is convenient. For example, 3/4 in the morning and 1/4 in the evening might work too. The smaller proportion should be in the evening. I switched back to taking my dose all in the morning when I could sleep all night without pain.