For that particular text it would naturally be "accordingly" "If we agree to meet at 4pm, I can plan my day around that (time)" time is optional "if we can meet at 4pm I can plan my day accordingly" around and accordingly are both equally used, but accordingly sounds natural for your particular sentence.

Hi, you can say one of two different things. 1. I need to plan my day around our meeting. 2. I need to plan my day accordingly. I would also say 'are we meeting tomorrow at 4 pm as discussed?' Good luck, Janie