Your ADR date is 3/1.
That is your 90-day mark.
The +10 thing means, since you are staying at a Disney resort (I assume so?), you may make up to ten days' worth of ADRs at that point.
Folks who do not stay in a Disney resort must call each day to make their ADRs, they cannot do ten days at once. They must call 90 days before the day they wish to dine at a specific restaurant, not 90 days before they first arrive in WDW.