Leaving Canada after applying for online citizenship application

[Sasasa]

Hi everyone,

I'm planning to submit my citizenship application online, but I have to travel in late October for 4.5 months.
Will that be a problem? Do I need to wait until I received my AOR before traveling?
Will it be better for me to apply after my travel?
If we applied online, does IRCC only contact us through email?

Can I please get some advice? Thank you in advance