6) if you have been lucky enough to receive an ITA, you then have 60 (sixty) calendar days to gather all of your documents (police clearance, medical checks, ECA assessment(s) & education transcripts, language tests etc) and submit them to the Government of Canada.Whilst 453 has been the lowest required score to be included for consideration for an Invitation to Apply, you must remember that there are only a certain number of invitations allotted for any given draw and, for each draw the applicants with the highest scores will receive the invitations... for example if Joe Immigrant scored 625 and entered the pool, he'd have to not only hope that he'd be eligible for the next draw, he would also have to hope that his score is high enough so that he would get an invitation... i.e. if the cut off was 623 and there were 500 invitations allotted for the draw, the chances are pretty slim that he'd get an invitation because even though he met the minimum score, it's more than likely that there are >500 people who have a score higher than 626, so he'd have to wait for the next draw and hope that it will be low enough so that his ranking is high enough to qualify. If the cut-off was 479 and there were 1200 ITA available, then Joe would likely receive an ITA, as there are lots of ITA assigned to the draw and it's likely that his 625 ranking is high enough to earn a spot to apply.
Always keep in mind that just because you meet the cut-off, it doesn't mean that you will receive an invitation to apply. You are competing with everyone else who wants to immigrate to Canada who has the same skills or better than you.
Your application is valid for a year, and during the year, you are welcome to improve your academic qualifications and your language scores/learn the other official language to a level of proficiency that will get you points.
At the end of that year, if you have not received an ITA, you will have to reapply to enter the pool and you will not receive an ITA just because you've been in the pool for a year... the CIC is only interested in your ranking score and they don't regard how long you've been in the pool as a reason for issuing you an ITA.