(SPOILER) Time line order from beginning to end from Li Zi Wei POV

While my memory still fresh, I'd placed my thoughts on Li Zi Wei correct timeline order here:
- 1998- LZW met a girl whom his bestfriend (MJJ) like named CYR, who later was hospitalized & after woke up become a girl named HYX who confessed come from the future 2019 & mistook him as her dead boyfriend WQX as according to her his face is similiar to WQX's
- 1998- LZW fell for HYX
- 1998- LZW met a 6 years old HYX who lost on the street, he helped her to find her way back home after giving her some treats (he left a memorable impression to the little 6years old HYX)
- 1999- HYX soul transferred back to 2019 (or being surpressed unconscious) & left CYR back to her own body
- 1999- The depressed CYR ask MJJ to kill her so that she'll be remembered in everyone's memory but won't be taken as a mere pitiful girl whom nobody wants whether when she lived or dead if she commited suicide
- 1999- CYR got stabbed & killed by MJJ.
- 1999 - MJJ got 9 years long jail sentenced, LZW lost his love & best friend
- 2003 - LZW back from Canada, visit MJJ in prison but MJJ refused, LZW got into a car accident on his way back & went into vegetative state for two years, while he was in coma, his soul was transferred into WQS body who survived after commiting suicide at the year of 2010
- 2010 - LZW in WQS body went to pursue the current HYX who met him for the first time as WQS, after went through so much effort & facing some rejection, he got her love, they dated & lived together for several years
- 2017 - HYX went to Shanghai for her carrier, WQS taking the next flight to catch her even after knowing that he'll die in the airplane crash if he's boarding in that flight, because his death will be the reason for the future 2019 HYX travelled back to the past & met the past LZW, the beginning of their love.
- 2017 - LZW journey as WQX ended at the airplane crash
- after the airplane crashed, LZW soul back to his own body & woke up at 2005
- 2005 - LZW got part of his body paralyzed after being coma for 2 years, he's taking rehab for years to be able to walk again
- 2008 - MJJ is released from the prison, LZW welcomed him back, MJJ grandmother passed away & later he commited suicide, LZW was unable to save MJJ/prevent his death & lost his best friend for good.
- during 2010 - 2017 LZW keep in contact with CYR uncle & he heard WQS & HYX story from him as well
- 2017- LZW met WQS for the last time to prevent him taking the flight but fail because WQS has determined to set his feet on board so the past him had the chance to meet the future HYX & the future him had the chance to stay on HYX side.
- 2019 - LZW finally met the present HYX who has learned the bigger picture of their love story after time travel back to the past, they reunited for a short time period but later he got killed and his life as LZW has ended there, until the world being reset once more & they met as a 28 years old LZW & 17 years old HYX and they start their journey once again after manage to save MJJ & CYR lifes ❤️

 Wndering Dragon:

Great summary!

Only MJJ didn't kill CYR, he failed to save her. 

It was both - she jumped, but he made it look like he killed her, why you see him being walked out of the building by the police covered in blood. She was not covered in blood herself and neither was he when you see him on the ground with her. 

There's also the previous scene where she's shown with the stab wound, though that seemed to have been on another loop, not the one we were shown, since it was on the higher floor of the building and not the ground. Because on every loop things change a little bit each time, that explains why what we were shown near the end was different from the beginning.

Wikipedia (https://en.m.wikipedia.org/wiki/Someday_Or_One_Day#:~:text=plot%outline%summary) also has a visual graphic of the loops, though not on a timeline. Timeline is better imo.