Waiting for at least 4 hours between these two procedures is a must. But that’s only when it’s urgent to get the hair color done. If it’s possible, you must wait for anywhere between 24 and 48 hours.
See, when you spa your hair, you go through a cream bath. If you have colored your hair immediately before that, this bath will take off the color, leaving a very timid coloring affect on the hair. So to get maximum result from your hair coloring, you must keep the right interval between the coloring process and the spa. The more the better! It will give time to the color to better settle and suit your hair.
Now note: these days you will easily find hair colors that provide extreme and sustaining result. They might not get off even after immediate spa. However, you’re usually advised to maintain a distance from these hard colors that include harmful chemicals that may ruin the nutrients and rich property of your hair.
In short, to answer your question—waiting for 4 hours is a must. If possible, wait for more than 24 hours.