First I would like to congratulate you on taking measures to avoid the CELBAN Trap. You have only been in Edmonton for such a short time, yet are making wise choices. Anxiety is a natural effect when it comes to the scores, and the probability of passing the CELBAN exam on the first attempt. There are very few people who can do this. You may be one of them, but it all depends on your predictive factors; there are 5 factors that determine whether or not you will fall into the CELBAN Trap. 
It is difficult to answer your question without knowing where you stand, when it comes to the language and the Canadian culture. Do you have scores for the IELTS back home?
In reading your email you are a strong writer. This is advantageous for you. It is a good foundation on which to build test taking strategies. As to how long it will take you to prepare, that is difficult to say. Would you like to get your writing assessed?
With an IEHP Writing Assessment (Internationally Educated Health Professionals) you receive:
- a formal assessment identifying your strengths and weaknesses when it comes to:
- Nouns & Articles,
- Verbs & Verbals,
- Agreement Errors,
- Advanced Punctuation, and
- other elements of grammar, punctuation, spelling and sentence structure.
- an assessment of your skills and abilities when it comes to Medical Documentation Standards, and
- Medical Collocations.
- an estimate of the amount of time it will take you to prepare for CELBAN Writing.
- recommendations to determine which of the CELBANPrep and IEHP writing resources and supports will assist you in obtaining your goal of passing CELBAN Writing.
The fact that you have already started your application with NNAS, and have the time pressure of one year (with the assessment fees being so high) you have exposed yourself to one of the predictive factors that increases your likelihood of falling into the CELBAN Trap by introducing a new stress factor. As I wrote to another IEN in answering her question When should I register with the [National Nursing Assessment Services]? it is best to limit this stress factor by applying to NNAS after you have achieved an accepted score on the CELBAN. But if you have already begin your process with NNAS that is water under the bridge if you are able to handle the stress of the deadline you have put before yourself. And that, my friend E, is the source of anxiety that counteracts your hope to pass the 
CELBAN on the first attempt.
So, let us go from here. Consider the possibility whether you would like to get your writing assessed. Then I will be able to provide solid advice, based on my six years of experience working with IENs preparing for the CELBAN.
One final word, in considering when you take the exam please do this one thing: take the exam only when you are confident you will pass! Your hope and confidence will override any anxiety and allow you to perform to the best of your abilities. And you will be protecting yourself from the grief, shame and depression that follows so many IENs who have failed this exam. Protect yourself. Avoid the CELBAN Trap. Be prepared and you will be confident!
Dear Kim 