until

*Can you please have that done until Tuesday?

Until is used when we talk about a continuing situation or state that will stop a certain moment in the future. By is used to talk about an action that will happen at or before a future moment. Compare:

Can you repair my watch by Tuesday? (Action)
No, I will need to keep it until Saturday. (Continuing state)

Can I stay until the weekend? (Continuing state)
Yes, but you have to leave by Monday midday at the latest. (Action)