As much as the topic has been discussed, I am surprised at the number of people who are either unaware of the March 22 American Airlines AAdvantage devaluation or who are unaware that said devaluation is one week away from taking effect. Most premium cabin rates are going up post-devaluation, many of them significantly, so if you have a large balance of AA miles and have future trips already in mind, you should definitely try to book an award prior to the devaluation.
You will be able to perform the same modifications that AA usually allows for free on awards, such as date and route changes, without triggering the post-devaluation rates, so even if your plans are somewhat in the air, it might be a good idea to secure something now and then eventually try to modify your award if necessary.
Another factor to keep in mind is that you need to complete your booking by March 21st in order to secure the pre-devaluation rates. Simply placing a hold on an award on or before said date will not result in securing the pre-devaluation rates if the award booking is subsequently completed on or after March 22nd.
On the other hand, with so many people trying to book awards before D-Day, I imagine that telephone wait times at AA will be exceptionally long beginning on Saturday and continuing all the way throughout March 21st. Therefore, if your award booking will require a phone call (remember that most AA partner awards cannot be booked online), try to complete your booking by Friday, March 18th.
If you have any questions regarding the AA devaluation, feel free to ask them in the comments section. I will try to respond as soon as possible.