Hi Chris, there is a FAQ in the DIAC website.
[h=3]Can I submit an EOI if I have not completed an English language test, skills assessment or Job Ready program?
[/h]No, not if you need these in order to submit an EOI.
If you are submitting an EOI for a points based visa, you must have completed an English language test, skills assessment or job ready program (if applicable) before you submit a complete EOI.
You do not need to attach documents to your EOI. However, you must enter accurate information in your EOI that matches the information on the supporting documents.
Hence you need to take the IELTS and the skills assessment before u can lodge your EOI. By the way, the IELTS results will be valid for 2 years.