Time is flying for Khloe Kardashian and Tristan Thompson … because she’s getting emotional over their daughter’s educational milestone.

Khloe and Tristan gave True a grand sendoff to first grade Tuesday, with a fancy photo shoot and gushing social media posts … and Khloe offered a glimpse into how she’s feeling as a mother.

KK says … “I’m not ok but I’ll pull it together by pick up time.”

The proud parents, who are separated but co-parenting, each shared a series of photos with True in her school uniform … cheesing for cameras in front of a background filled with balloons, giant crayons and a “First Day of First Grade” sign.

Khloe and Tristan took turns squatting down and hugging True … and her little brother Tatum even made some photo appearances … ditto for her pet cat.

Tristan got emotional too, mentioning his late mother in his post … “I know Gigi’s looking down on you and she is sooo proud of you and how amazing you are and how you’re the best big sister.”