No need to purchase a flight ticket for now. You can grab one from Expedia (or similar sites) or just make a screenshot of the flight schedule you want from your chosen airline.
As for itinerary, yes you can just create a day to day sched.
Example :
Day 1 Arrival from (country of residence)
Day 2 - 4 Sleep/ Adjust to jetlag
Day 5 -9 Visit Niagara Falls