Your question is too general you need to decide on province/city first then you need to research colleges that offer the specific course you are looking for. Having done that the college website will usually indicate if they are still accepting applications for September.
As per Canuck with 4 years SW experience already your SOP will need to be convincing if just going for another SW course whereas a masters or project management for example might be convincing. Nobody here can really second guess your SOP will be successful or not.