Contacts work like this..
If you're transitioning from glasses, you're not blinking nearly as much as -Normal people' or 'the long time contact wearers'
glasses keep your eyes m0ar wet, thereby reducing the need to blink.
So, without the blinking and suddenly no moisture shield from your glasses, what happens is, your contacts will dry, thereby changing its shape slightly , and blurring your vision..
The dryness may also cause it to shift out of alignment on your eye.
If you continue to wear them, your eyes should naturally blink more and produce more tears.