I know how to reset for campers, but ok. So you're at March 30 at this point.
Still at March 30 (?). But why did you do the bolded part, and more importantly why only one minute?

; I'm curious as to the point of it. What time was it exactly?
Doing this wrong, if I recall, can count as anytime backward and the game can mistake you moving backwards for one whole day. You last played at March 30, 22:00pm, then changed the time to March 30, 21:59pm?
All this tells me is you made an error in time traveling at least once. You time traveled between lots of days and saw that the errors are still in (29) which means you have been to (29) at least once, hence why you have that notice from Nooklings. In one of your TTs you have saved in (29) and have not watered your flowers prior to going back to the real time thus the missing/wilting flowers.
No, um, TTing anytime backwards will always count as a day forward. So going to a previous day would just be a "new day" and so the "future stuff" will still be there. Regardless of whether you use in-game or system clock.
Example: You planted hybrids on March 31. When you TT back to Jan 31, 2011 the hybrids will still be there.
Sorry, I'm really trying to help by getting to the bottom of this, but there's too much and too less information to go on. :C