Yes, IRCC only requires an applicant to show funds for the first year, and if you are inital application is for a one-year program I think you are good to go. However, what I have heard from different agents that if an applicant is applying for a program for more than a year, it is required to show accessible funds for the entire duration.
One more thing is you said you will be doing an extension to the study permit to complete further studies later, I think when you step foot in Canada things become very easier when it comes to doing applications within Canada.