Three things I've already done today:

a. I've already had breakfast with my family.

b. I've completed some work tasks for the morning.

c. I've taken a short walk in the park to get some fresh air.

Three things I haven't done yet, but which I am going to do today:

a. I haven't exercised yet, but I plan to go for a run later.

b. I haven't made a grocery shopping list, but I'll do it before heading to the store.

c. I haven't called my friend to catch up, but I intend to do so this evening.

One thing I've just done:

a. I just finished replying to your question about my daily activities.