I have planted them in May before and got bulbs with cloves , so anything can happen .
They may just not form cloves , but you should get , at worst , a garlic like a pickling onion , ie one big round clove .
Perfectly ok to use , it is still garlic , freshly lifted they can be eaten raw or roasted , or used as normal , they may not keep quite as long ?
They may form cloves but be about half the size of a normal bulb .
Always worth a go though , even cloves that sprout in june , july etc can be put in pots or trays and just cut the growth like chives .
You don't get a bulb then though , just cut and use the top growth , then bin them when they flag .