That's in the evening of 4th July for anyone in the US. A British-made engine will fire to slow down Juno enough for it to enter Jupiter's orbit. NASA engineers refer to this as the "orbit insertion burn".
The "orbit insertion burn" will last for 35 minutes and is the most crucial manoeuvre in the mission so far. If this goes wrong Juno will sail past Jupiter into the abyss of deep space, and it will all have been for nothing.