Something lost in translation?

I have downloaded a “toddlers knitted hooded jacket pattern” from a “French” site. I now can not access this site again.
I am up to knitting the hood. [FONT=“Arial Black”]The pattern says “with 5mm needles, cast on 92 sts & work in garter st. In total 3 cm in ht, decrease on each side, 1 st all 8 rows (6 more time) Continue until 20cm in ht. Bind off 80 stitches”.
Gauge is 17st & 30 rows to 10cm square, in garter stitich on 5mm needles.[/FONT]

Has something being lost in translation from French to English?

Do I knit in garter stitch until work measures 3cm, then decrease at each side 1 stitch for the next 6 or 8 rows? (6 rows will remove 12 stitches!).
Do I start decreasing from the first row? as decreasing each side for 6 rows will give me b a height of nearly 3 cm.
Is all 8 rows a mistake?

I am knitting for my first grandchild and haven’t knit for about 30yrs.

Welcome to KH. Does your pattern have a name so that it might be possible to find a picture online? Do you even have a picture with the pattern? If so you might see if it looks like there is a band at the bottom of the hood before the decreases start. Don’t worry, there are very skilled knitters here who can either help you figure out what this means or knit a lovely hood anyhow. I hope you’ll post a picture when it’s done.

A big “Thank you” for your prompt reply. I did go to the site to see if I could “blow up” the pattern I had printed, but I can no longer access it. I regret did not “save” the original download and the print is too poor to see where the hood joins. The pattern also said "[B]Neckedge: total 28cm in ht, bind of every alternate row: 4 sts (1 more time), 3 sts (1 more time), 2 sts (1 more time) 1 st (2 more time) Bind off 17 stitches of the shoulder[/B] I started with 28 sts, so I obviously only cast off, 4, 3, 2 1 & 1 stitches only.
The hood will be quite large. What way will fold nicer?

Welcome to the forum!
I would make the decreases at each end of the row on the fir 3cm in ht. That gives you a shaped band at the beginning of the hood.
If there are later directions for seaming this to the neckline, place the seam to the inside of the hood and sweater.