First, you can lift restrictions way before you reach 50% vaccination, since 50-60% should give you plenty of herd immunity, and definitely much better than the stupid “wear a mask” rule is giving you.
Second, each manufacturer is expected enough doses to do 20-50 million people before december 31st. We only have 300 million people, so that is 1/6th of the population.
Third, by march there should be at least one more vaccine, again with pre-made 100 million doses.
There is no reason we could not vaccinate our entire population by april, if we wanted and people were willing.
Many people will be unwilling if they keep hearing FauXi, Levine, and the other Doctor Dooms saying that masks, closures, etc, will continue even AFTER a vaccine.
They will rightly say...what's the use?