I'll just comment with some observations/tips I've come to know from doing Matsuri.

I'm obviously not 100% sure on whether Matsuri is based on level or not, it's definitely not based on power as the opponents you get are too varied in power for it to be, but I don't think I've ever went against a level "70" as a level "90", so we can assume it chooses people within your level range at the very least.
What is the average power on your server compared to the average level? Its a good way to gauge if you're behind the curve or not.
I think 100k at level 99 is quite low power personally, but I'm comparing that with myself & those on my server, most people on my server around level 85-92 are about 90-100k power.
So I have 100k power & I'm level 92, I've been winning Matsuri pretty consistently since level 79 (44k bp), I'd say I win at least 2 full Matsuris out of 3- that said I do have bad weeks, I have went a week with 0 Matsuri wins, it is RNG after all.

What most people don't know is that Matsuri can be manipulated to an extent, the game attempts to feed you free wins & you can manipulate this if you have somewhat decent teams & reasonable power for your level.

Keep in mind that I've heard of hugely varying results and many factors could play into Matsuri that I can't account for, but I've always had consistent results myself.
I'll do my best to explain.

So to begin I want to address something that others have said, I always do my Matsuri as soon as it comes up, I never wait 30 minutes, or an hour, I always try and attempt it during the highest possible player count which I assume is exactly when the event starts, the reason for this is due to the sheer volume of players, match making will work better if there's a larger volume of players to work with as that's how it works, obviously I'm making the assumption that there is match making, but if there is no MM(Match Making), then you still want to do it during peak as there will always be less whales on average than there are normal players, you're trying to maximize your likely hood of going against someone you can beat & having a larger pool of players to choose from makes it easier on the MM when it comes to you getting your "Free Win", which the system does try & give you, also the assumption that all the Whales do Matsuri instantly so waiting will allow you to bypass them is based on the assumption that all whales for some strange reason do their Matsuri differently than everyone else, some wait- some don't, you still want a larger pool of players to drown out getting a whale and to reinforce your chance of getting that "Free Win".

I see no solid reasoning behind waiting to do it later, rather than doing it sooner.

- Your first fight should usually be a win, it can happen that it isn't but generally I've noticed on average it puts you with someone on your own power or lower but I've heard from others that they rarely get a win on their first fight. It has happened to me as well but generally speaking I usually get a victory here so I'll use this as a baseline, assuming that Match Making is loosely based on levels, if you aren't winning this fight consistently then we can assume you're on average lower in power than those on a similar level to you.

- This is also based on you having a reasonable team (Obviously)- generally a fight is dictated by initiative alone, assuming both teams have a reasonable line up. There are exceptions to this but they are rare, you can beat someone 20k power head of you if you have a line up that straight up counters him but we can't create accurate results with that we can with Initiative & Power. If you can confidently say you are at least ranking on average similarly to those of your own level in Power & Initiative, I see no reason why you shouldn't be winning at least 40-60% of your Matsuris.

- After you've won, it puts you against a random person, once you've lost it should "normally" put you against someone you're likely to beat(Free Win condition), this is what you can manipulate to your advantage.

- Start with your best team, end Matsuri reviving your best team- This is because of the first win rule & the free win mechanic set in place after you lose a fight, you want to guarantee that first win, then queuing for a 2nd fight should theoretically be your "Loss" fight, generally after winning this fight I guarantee I'll win Matsuri with 90% accuracy. The third fight is usually where I lose my best team & where my 2nd team will gain a win, which will then lose. This pattern leads to the reviving team getting the "Free Win" which in most cases solidifies your 5th win & if not it should be your 4th with you then fighting your 5th fight with your best team.