Sorcerers Apprentice
Hero
The article linked in the OP explains how to convert XP to ACP:
Converting Your Current Experience
To determine the number of Advancement Checkpoints your characters currently has, follow these simple steps.
Find the experience your character has in excess of that which is required for their current level by subtracting the experience needed to achieve your current level from your current total.
Find the experience you need to achieve your next level by subtracting the experience needed to achieve your current level from the experience needed to achieve your next level.
Determine how far into your level you are by dividing the result of step 1 by the result of step 2.
To determine the number of advancement checkpoints you now have, multiply the result of step 3 by the number of experience checkpoints needed to achieve your next level.
If the result of step for is not an integer, round the result down or up. (Your choice.)
If you wish to use the Slow Progression, divide your result by 2.
Example: Your character is currently level 6 with 17,000 xp and you are not using the Slow Progression option.
Your character has 3,000 xp more than the 14,000 xp needed to achieve level 6. (17,000 xp – 14,000 xp)
Level 7 requires 23,000 xp; 9,000 xp over the amount needed for level 6. (23,000 xp – 14,000 xp)
Your character is 33% of the way to level 7. (3,000 xp / 9,000 xp = 0.33)
In the new system, it takes 8 check points to gain 7th level. You currently have 2.64 check points (0.33 * 8).
You choose to round up. Your character has 3 checkpoints of the 8 that they need to make it to level 7.