I'm thinking of Time Travelling.  Tell me why I should NOT do it.  

It's up to you what you do - whilst the game-designers are clear about their intent for the design of the game (it's a real-time persistent-world game), the options are there for you to do whatever you prefer (you can choose a different hemisphere to your own when you first start playing, there's an in-game drop-box for late-night selling of items, and you can change your console's clock if you want to), so it's entirely up to you how you want to play.

Animal Crossing is a doll-house (specifically, its aesthetics are based on 1968's Nintendo People House), combined with a toy-box, combined with digital bubble-wrap. That last bit is key. Some people like to pop bubble-wrap by hand, one bubble at a time, and others like to roll it out on the floor and walk on it.

Do what makes you happy and is the most fun for you.

Thanks PennyGwin. Love the bubble wrap reference! 😂
Can anyone tell me what bad things could happen if I do TT?

TT I believe bars you from participation in holidays. People I heard did not see Zipper if they were in an alternate time from their auto updated switch time. Time traveling beyond that doesn't have really any game breaking risks. Each day you TT it resets your turnip prices now. I have noticed that coming into Sunday after a TT my turnips for the week seem to usually be on a steady decline cycle. They patched the bank interest to prevent massive time hops for interest profit. Previously TT'ing back a day counted kind of the same as traveling forward. It would advance a day on your "7+ day check in at the atm for nook miles". This was patched and now TT'ing backwards doesn't count as anything. TT'ing forwards has the same results as a normal day progression. Flowers still grow, trees, etc. Your items in the Nook store are also locked. Timmy and Tommy will have the same items if you TT forward and back. If you buy something on Tues. hop to wed. then hop back to tues. that item will still be gone where you had bought it. I have seen it break this treand if you traveled forward a great amount like a month and traveled back to that previous day, it would actually reset your weekly nook shop items, I haven't confirmed that since further patches. Ables will still cycle their clothes randomly like normal. Nook Mike items and nook special order items still cycle as normal.

Edit: also your bells tree spot/ glowing spot spawns each day regardless of TT. So you could essentially farm bell trees by just hoping between the same 2 days. Your fossils also respawn if you change the date. Even if you go backwards. If you have a villager in boxes say Lolly on the 22nd, as long as you don't load the game when the date is anything but that day she will still be in boxes. So you can hop between morning and night on the same day without changing anything that happened that day. So with a fishing tournament you could roll the time back a few hours and give yourself more time to complete the event. I am not sure how TT'ING affects Lilly of the valley. I have gotten two from TT'ing forwards but haven't seen any going back in time. Your next 5 top nook mile activities will change with each hop of the date. Those reset on the start of a day same as the fossils and bell tree spot.

Any other questions just ask.

TTing backwards can spoil any turnips you have, and I know the mail your mom sends you can only be gotten once a year. so say you travel past your birthday, you'll get your birthday cake, but you won't get it again when your birthday comes around for real. I think there might be other events that are once per year only, but I don't know what they are. either way, you still get to experience them if you TT, you just won't get them again when that day passes again.

I know most of the usual pitfalls of TTing have been removed. flowers don't wilt anymore, you can't get more than 150 naturally spawning weeds, villagers don't move out without telling you and you don't lose friendship if you go a long time without talking to a villager. there isn't really a whole lotta harm you can do

Excellent!  Thanks guys. This is exactly the type of info I was looking for.