Welcome to the forum and congrats on your recent wedding!
You can definitely fill out the forms and start getting all your answers/dates/info ready, but I would wait until closer to the time you will be submitting to print off and sign your final copies of everything. CIC has been known to change/update the required forms randomly and if you submit your application with an outdated form you risk having the whole package returned to you. There's a chance they won't care and will still proceed with the application, but this process is stressful enough without having to sit and worry about your application being returned over an updated form.
But I would definitely start preparing ahead of time and getting all your forms filled out, just save them on your computer and double check that the versions you've been working on are the most recent ones before you print them out
Best of luck, and keep us posted!