Here's a rough schedule:
March/April: Get LORs and transcripts sent in (except the one at the school you're still attending classes at). Start drafting essay, get some dental experience if you don't have any. *Note: It is helpful if you request unofficial transcripts from all schools attended to be sent to you so you can fill out your AADSAS application. You must report all classes and the dates they were taken, and that's somewhat of a hassle if you don't have documentation right in front of you.
Middle May: Start AADSAS, think about schools you want to attend. Finish up essay. Keep shadowing a dentist. Follow up on LORs and transcripts.
Early June: Submit AADSAS application. Make sure all LORs and transcripts (even transcripts for the classes you just finished) are sent to AADSAS.
Middle June: Call AADSAS. Ask them what is missing still. Think about sending in secondary application fees to schools you applied for, even if they haven't asked for them yet. Call them to ask how much they are.
July-??: Sit back and wait for interview invitations to come in.
October-November: Go interviewing. =) Travel, enjoy, see the schools, stay the weekend, get to know your schools. Spend extra time at your top choices. Make sure you want to go there.
December 1: Get notified of your acceptances.
December 5-10: Send in deposits. Send in Intent to Register letter. Breathe. Smile. Party.
That's just a brief outline of a good (im my opinion) timeline on the application cycle. Please add what I've missed!!
Good luck. =)