Hello, based on the CIC online information (see copied/pasted info below), I did go ahead an updated CIC/IRCC regarding my new job (principal applicant, March applicant) by uploading a scanned copy of my job offer letter, first payroll stub, and a brief note explaining that I have recently started a new job and will provide a job letter as soon as I complete my probationary period at work.
CIC responded to me via email that they have received my update and documents.
I think that it helps your application whenever you provide positive updates, such as new employment, and it provides them with an update regarding what you submitted in your original application regarding your work history.
Copied/Pasted online info:
How can I update or ask about an IRCC application in progress?
If your application is already in progress, use the
Client Application Status (CAS) service. This service lets you view the status of your immigration and/or citizenship application online.
You can also use this
web form if:
- you want to report important changes about your application, such as:
- births
- deaths
- marriages
- divorces
- adoptions
- changes in address
- changes in employment
- a new educational credential
- results of an approved language test