Speed Up the First Time Machine Back Up

Because of Time Machine's incremental backup method, only a small amount of data needs to be sent over your network to backup to a wireless Time Machine.  You can connect a disk to your router or Airport, click a few buttons and you'll have a reoccurring wireless backup system.  While this generally works out very well, that initial backup to Time Machine has to copy all your files and can take forever!  Even if you're connected via ethernet you'll looking at a great deal of transfer time.  This little trick will make that first backup incredibly faster.

Step 1. With the hard drive connected to your router, open up the Time Machine preferences on your computer.  Click the Change Disk button.

Step 2. Select the wireless Time Machine drive and click "Use for Backup".  You may need to enter your password.  If you don't see it in the options, open Finder and go to your network (under the Shared section of the left hand side).  Double click the folder of the hard drive you'd like to use for Time Machine.  It should now be selectable in the Time Machine preferences.

Step 3. Wait for Time Machine to begin backing up or just click "Back Up Now" from the Time Machine icon in the menu bar.

Step 4. Time machine will spend a little time creating a sparseimage on your disk.  While it's doing this, the transfer window will list the status as "Preparing". Once the progress bar switched from "Preparing" to a data transfer, stop the backup.  The best way to do this is to go to the Time Machine icon in the menu bar and click "Stop Backing Up".

Step 5. It will take several seconds to finish.  Once it's no longer backing up, eject the Time Machine disk.

Step 6. Disconnect the Time Machine hard drive from your router and connect it to your computer.

Step 7. Force a backup by going to to the Time Machine icon in the menubar and clicking "Back Up Now".  In most cases, Time Machine will recognize the drive and start backing up over USB at a much faster rate. When it's done transferring all the files, simple eject the hard drive from your computer and plug it back into your router.  

Additional Tips

Time Machine may fail to find your backup once you connect it to your computer.  If this is the case, go into the preferences and change your disk to the one that you plugged in.  Time Machine will then find the sparseimage and backup.  Repeat this step again once you plug it back into the router.