The rules on Two-Weapon Fighting state:
When you take the Attack action and attack with a light melee weapon that you’re holding in one hand, you can use a bonus action to attack with a different light melee weapon that you’re holding in the other hand.
However, the description of bonus actions states:
You choose when to take a bonus action during your turn, unless the bonus action’s timing is specified
So, can you attack with your bonus action first?