That age group does not "get" time. They are learning..... Slowly
I'm a 13yr substitute for 1st grade. We don't count the children tardy if they are in the hall putting things away in the lockers. We do push them to hurry up, do lunch/attendance count. We make this a morning effort to do better everyday .
The only tardy comes if a child is dropped off after the last bell and has to check in with the office.
We have a reward jar in the room. When everyone is in the room on time, starting on morning work and on time for announcements..., maximum reward goes in the jar! This reward is typically for a popcorn party and movie during an afternoon or something like that.
Bottom line the children work together to make sure they get maximum marbles or whatever we have in the jar.
It's interesting to watch the always punctual children go to the hall to help others get in class and get started so they get the reward. They work together and that's another positive!!
I don't know how to help at home in your case. My daughter is now 19 and living in her own for college. Many years I did start making her go to bed earlier if she couldn't get up and going on time. My daughter cherishes her sleep to this day and she plans her schedule around it!!!
Side note...... I appreciate you being on this site. You've given some great advice to those of us who have pets. You can't diagnose anything of course but you have given some options and ideas. We just lost our 14.5 yr old dog in Dec and it was heartbreaking and in the middle of an ice storm. We had the poodle on recovery from cataract surgery so our last 3 months have been very pet related.
Best wishes to you!