How many seconds usually takes an email to get to an outlook account?


Outlook version
Email Account
Exchange Server
I know this is not a question to be answered precisely, I just wanted to ask you if you know, as an average, how many seconds does it usually take if I send out an email using yahoo till it reaches the inbox of an outlook account? I have to send an email that has to be received at a certain hour, no earlier than that and I am not sure, to be safe, how many seconds in advance should I send it. I know there may be routers and all sorts of firewalls in the way, but just approximately, just to be sure?! If my email has to be there at say 17.00.00, is it safe to send it at 16.59.52 for example? It's not the same server and it's not even the same country, and at that time a lot of other people will send emails to that address, probably hundreds... Thank you.