NEED help i need a Diag on this PLANT!!!!

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Hey peeps.........

I,m 1 week into flowering..........ive got 90cm in total hight , got 40 cm left.....
whats the latest to top them plants....(they just started showing pistals....)

i,m worried bout my hight

so i got 1/2 my growspace left(40cm)
oh its a Swazi (sativa)...