Are you sure you wouldn't prefer to arrive at Aix-en-Provence Ville (city center) ? Otherwise you would have to pay a lot of money for a small TGV ride to arrive in the middle of nowhere (TGV station).

Schedule example :

- IC Milano Centrale - Ventimiglia 07:10 - 10:54 3€ (book through ÖBB)

- TER Ventimiglia - Nice-Ville 11:16 - 12:11

- TER Nice-Ville - Marseille-St-Charles 13:25 - 16:03

- TER Marseille-St-Charles - Aix-en-Provence Ville 16:41 - 17:21

OR (you can decide on the day)

- TER Nice-Ville - Marseille-St-Charles 14:25 - 17:06

- TER Marseille-St-Charles - Aix-en-Provence Ville 17:23 - 18:09

There would also be a later connection, leaving Milan at 11:10 and arriving in Aix at 21:39.

Expect trains to be quite busy that weekend, start of the summer holidays in many places. Where are you heading afterwards ? If you'd like to take a TGV high-speed train to Paris, better book it in advance. But don't worry, there will be last-minute availability via Lyon (just a bit longer).

We are meeting friends and that is the station they have told us to go to!

Well it's not very practical but here would be a connection that works :

- TGV Marseille-St-Charles - Aix-en-Provence TGV 17:36 - 17:52 20€ (for such a short journey)

OR actually better if you board it in Nice directly to enjoy the comfy seats of the TGV

- TGV Nice-Ville - Aix-en-Provence TGV 14:40 - 17:52 20€

However you could save those 2 x 20€ easily.

I have asked my friend if they could pick us up from Aix-en-Provence Ville instead! We will see what they say! 
So with your schedule, we would only need to reserve seats from Milan to Ventimiglia? Is that correct? The rest of the trains we just go to the platform and hop on with our rail pass? 
And could we do this trip earlier? Say leaving at 6/6:30am?

Yes exactly, 3€ for this train through ÖBB. You add all trains you'd like to take to the app before boarding, this gives you a QR-code (your ticket). Then hop on and sit wherever you want.

There may or may not be 1st class seats on French regional trains : some do, some don't. Worst case : you can always sit in 2nd class. :)

Nope, not possible to leave earlier. There are not that many trains in the region unfortunately.

Our friend said she can meet us at Aix-en-Provence Ville!! So we should use your first schedule? 

Yes, you'll arrive in Aix at either 17:21 or 18:09 depending on whether you'd like to take a break in Nice or not. :)

Thank you so much for all of your help!