The escape from Malfoy Manor took place at the very end of March, 1998. So it's likely that Ollivander presented Luna with her new wand in April.
Luna receives a new wand from Ollivander
Date April, 1998
Certainty Inferred from canon
Location in Canon DH26: Gringotts
Type of Event Wizarding world
The wand wood and core of Luna's new wand is not mentioned in the text.