Did Snape give Voldemort the wrong date?

In order to preserve his position as a trusted Death Eater, Severus Snape was forced to tell Voldemort the true date at which the Order planned to move Harry. Harry himself did not like the plan because it risked others’ lives, but was overruled.

Was Snape originally a Death Eater?

Harry later discovered that Snape was once a Death Eater but had been vouched for by Dumbledore. Dumbledore told the Wizengamot that although Snape had indeed worked for Voldemort, he changed sides and turned spy against him.

Why didn’t Voldemort kill Snape as soon as possible?

Snape wasn’t even pretending to be a double agent during Philosopher’s Stone, so why Voldemort didn’t kill Snape as soon as he was physically able, or have Quirrell attempt to kill him, is unclear. So yes, why didn’t Voldemort suspect Snape as a double agent during the events of Philosopher’s Stone?

Why did Voldemort keep the Quirrell stone?

Voldemort must have thought that Snape didn’t know Voldemort was inside the body of Quirrell, He just had to keep the stone safe, because he wouldn’t get trusted by dumbledore.

Why didn’t Snape turn to Dumbledore for the Quirrell stone?

Ultimately though, had Snape, from Voldemort’s perspective, truly considered Quirrell an objective danger to Dumbledore’s plans for the stone, Snape would have turned to Dumbledore. Instead, Snape seems to be pursuing this on his own, which logically means Snape isn’t looking out for Dumbledore’s plans, but his (Snape’s) own plans.

How many times did Snape attack Quirrell in Harry Potter?

Snape cornered Quirrell more than once (Halloween, when Quirrell let the troll in, and the night Harry broke into the Restricted Section over the Christmas holidays to look for information on Nicholas Flamel) and openly threatened him against working for Voldemort and pressuring him to declare his loyalties to Dumbledore.