Growing true seed garlic is as experimental as it is rewarding. It is not like growing onions. Please see the following article and please take its recommendations seriously. It is easy to fail if particular steps are left out of the process.
“True Garlic Seed has a low germination rate. With each generation germ rate improves but expect as low as 15% and as high as 40%. Seeds require vernalization (aka. stratification). Soak seeds in a 1% bleach solution followed by a rinse and a month under refrigeration before seeding into flats or plugs. Germination is inconsistent and can occur from a few days, a few weeks and even a couple months.”
Seeds should be vernalized (aka. stratified) immediately upon arrival.