Saving time to do the things that you love is the point of planning ahead. A simple hack that saves both time and space is to only use part of a date or time when the rest of the page indicates the rest of the necessary information.
For example, instead of writing that you have a doctor's appointment at 10:15 a.m. on Thursday, December 18, 2014, you can write in the monthly calendar square (so that you already KNOW the date from the calendar) "10:15 Dr. Smith." The a.m. is not necessary as doctors generally don't schedule appointments at 10:15 p.m.
Here are some examples from my planner of shortcuts for writing dates and times.
*Drop the ":00" after an on-the-hour appointment and drop the "a.m." or "p.m." if the time obviously refers to one or the other.
*For a checklist of chores for the month, label the month once at the top, then just use the numbers 1 - 31 (or 30...or 29 for February to account for leap years).
*For temporary lists that are month-specific (like your Christmas gift list) or that repeat the same way every month (like a general bills due list of dates), use the numbers 1 - 31 (or 30...or 29 for February to account for leap years).
*When writing in a monthly budget page in your planner, only use one number to indicate the date.
In the example, December 1st and 2nd become 1 and 2.
*On yearly recurring event pages (listing birthdays, anniversaries, etc.), label the month once at the top, then just use the numbers 1 - 31 (or 30...or 29 for February to account for leap years).
*On Future pages that are already labeled with the year and month, write only numbers 1 - 31 (or as needed).
Of course, sometimes you really do need to know the exact date or time, as in my 2016 and beyond Future page. In those cases, write all the information that you need.
The point is to write as little as possible for saving time and space in your planner, but to write enough so that you are sure of the time and date. Sometimes, that means writing 11/30/14 at 12:45 p.m.; sometimes, that means writing 30...12:45.