So I'll say off the bat I'm not landing in July hence not replying before. I'm landing in June (unless my 6 week pending CSE reveals I need an updated CoPR which means I'll be lucky to land this side of 2017).
I have a few thoughts though.
Firstly get your tickets now, or at least asap. Flights go up in price as the date approaches and especially as this time of year which is peak tourist season. You really want to be booking > 4 weeks out, >2 weeks minimum. Tickets go up literally 50-100% < 6 days out. More if you are wanting something other than economy class.
Also on flights. Check return tickets. BA and AC are cheaper return than one way. Book the return "tango" if possible as you can't normally cancel a half-used ticket and that's the cheapest option.
Or... look at other carriers. Icelandic Air serve most of Europe and are generally fine one way. United tends to be reasonable one way too, though I've not tried them internationally.
July is going to be hot and humid. Expect it will hit 40C with humidity at least one week.
Moving alone has advantages for sure, but don't underestimate the impact of moving country alone and not knowing anyone and not having a job. And being apart from your spouse and 2 year old son especially if you haven't been apart from him for long before.
In my opinion, Spring (April) is the best time to arrive as you get limited cold weather and the longest gap before it gets cold. It depends what you are used to of course!
I would not recommend arriving November->Feb. This year was very mild, the two before... I don't think it went above 0 for 3 months.
I'd advise against a hotel for more than a few days unless fairly well off. Very expensive in Toronto and then you often have to eat out every meal unless you pay even more for a decent option with fridge etc..
I found AirBnb challenging because it was so small, but it was also about 30% of the cost.