There is a clearly indication that::
If your application falls under Category 1…
Send the following: 1 • the application forms, (You are in an occupation which corresponds to the list of occupations identified in the Ministerial Instructions) • a photocopy of your passport’s bio-data page, (principal applicant only) • 2 self-addressed mailing labels one in English or French and the second in the official language of your country, and • the payment.
"Do not send other supporting documents. Wait until you receive correspondence from the CIU in Sydney, Nova Scotia Canada"
So, i think u can sit for IELTS after lodging the application.