Kylie Jenner can't believe how quickly her baby daughter Stormi is growing.

The reality TV star - who will soon be celebrating a milestone of her own when she turns 21 on August 10 - got sentimental on Twitter to reflect on the changes that the tot has already gone through.

She tweeted: ''Stormi will be 6 months in 6 days ... how did this happen? Moms, do your babies grow as fast as mine?''

The 'Keeping Up with the Kardashians' star was flooded with responses from other mothers, who agreed with her sentiment.

One fan wrote: ''yess... I have two girls (11&16) Being a single mom is hard... But I live for my daughters.. They do grow up fast & I enjoy every minute w/ them. Be a mom but don't be tooo strict, communicate w/ them, show them lots of love & let them know you will always be there for them. [sic]''

Another replied: ''Babies have this habit of growing up in the blink of an eye! Cherish every moment!''

The makeup entrepreneur also inferred that her daughter, who she had with Travis Scott, would celebrate her first birthday in style.

A follower wrote to her: ''I'm just waiting on her first birthday party.''

To which Kylie replied: ''It's about to be lit.''

When Kylie turns 21 next month she will finally be legally allowed to drink alcohol in the United States and she has posted a photo on her Instagram story of a bottle Don Julio 1942 Tequila, engraved with her name.

The 'Life of Kylie' star has also treated herself to a makeover for her G-Class Mercedes Benz and Ferrari which she has had repainted in matching burnt orange.

The star posted a photo of herself posing with the cars, with the caption ''just for the summer''.