As others reference, the whole process is currently subject to disruptions related to Covid-19. It is difficult to forecast when IRCC will resume interviews and testing. So, for the time being, there is not a direct answer to your question.
That does not warrant the hijacking of this topic away from addressing your question, let alone using it to broadcast grossly misleading propaganda and fear-mongering. Sorry your query was diverted.
For when IRCC resumes interviews and testing citizenship applicants . . .
Hello, Can someone tell how long before we get the notice to appear for test and oath ceremony ? If one is outside of country, is it long enough notification to come and do it ? Is there any way to request long notice period like three weeks prior to Test and Ceremony ?
In normal times the amount of notice varies considerably. Generally there should be at least two weeks notice for scheduled events. Many get more notice than that. But some, it sometimes appears, may get less.
CAUTION: be aware that difficulty returning to Canada in time to attend a scheduled event is one of the biggest risks taken by an applicant going abroad for an extended period of time while the application is pending. There is some flexibility wired into the procedure. For example, applicants who missed a scheduled interview and test are generally rescheduled without a problem. At least once. But there are additional logistical and some non-routine processing risks involved if the applicant is living or working abroad while an application is pending. These issues are discussed in more depth in other topics.
In particular, if your plan is to live abroad while the application is pending, many do this and things go OK, but this has risks and for more than a few results in complications. Again, see in-depth discussions about this in other topics.
TEMPORARY TRAVEL ABROAD:
Many label going abroad as "traveling" abroad even if they are actually living or working abroad. However one labels it, there is a real difference between traveling abroad while the citizenship application is pending versus going abroad for a long enough period of time it amounts to living abroad. The latter I addressed above.
If the applicant is traveling abroad, only traveling abroad (not staying abroad for extended period of time), IRCC advises applicants to notify them of the trip. The idea is to give IRCC sufficient notice so IRCC will not schedule events, like interviews and testing, while the applicant is abroad. Anecdotal reports about how this goes vary considerably, with some reports that IRCC went ahead and scheduled the applicant for an event on a date the applicant had given notice to IRCC about being abroad. But it probably works most of the time.
In any event, that is the prudent approach. If, for example, you are traveling abroad for six weeks, if you properly submit this information to IRCC including dates, you should not be scheduled for the test during that time. Little need to worry about having to cut the trip short and rush to Canada on short notice.