The first part of this side quest can be completed after completing the events at the Tomb of the King Raithwall (and the Shiva airship) and before you complete the events at Mt Bur-Omisace. Head back to Nalbina Town to the front gates (listed as West Barbican on the map).
Walk towards the two Imperial Guards blocking the pathway to the northwest to initiate a short cutscene between the two of them. Fans of the Final Fantasy series will note that the letters in their names (Gibbs and Deweg) are very similar to those of two reoccurring characters named Biggs and Wedge that appear in nearly every episode of the game.
The scene will cut over to a young girl named July who is listening in on the conversation. Go over and speak to her and she will tell you that she is busy.
Next, walk over to Gurdy, the flying Moogle that is floating in front of the Chocobos in the pen and rent a Chocobo from him for 800 gil. Ride the Chocobo towards Gibbs and Deweg to initiate another cutscene.
Gibbs will take off running to ensure that he doesn’t get any of the Chocobo’s smell on him and Deweg will chase after him. July will speak to you one more time mentioning that she hopes to run into you later on in the game.
This is as much of the side quest as you can complete at this point in the game until you meet up with July in Archades. Click on the following link to return to the Rabanastre walkthrough page in Section 3.
Travel to Charlotte’s Magickery shop once you reach Archades and search for July. Speak to her one more time and she will reward you with a 
Salamand Halcyon which is a key ingredient for some of the powerful items in the Bazaar.
This completes the July side quest.
