https://www.canada.ca/en/immigratio...vices/application/check-processing-times.html
IRCC says five months, but could be longer if outside Canada/USA.
In practice, IRCC usually posts a timeline that covers about 80% of apps, and most of those are processed somewhat quicker.
Now note: if applying from India and you want to bring the child to Canada sooner, check with the consular section of the High Commission (or a consulate). In most cases when parentage is clearly established (eg parents married and birth certificate confirms name of Canadian parent), one can apply for a (temporary) passport on the basis of the citizenship certificate application (keep copies! to submit with the temporary passport app).
If all in order, they will / can issue this passport more quickly on the basis that the child is a citizen by birth (presumed citizenship, although that's not a formal term) who is just waiting for the certificate. Passports for infants are typically only one or two year validity anyway, so not a big inconvenience.