I am being treated with IPL for hyperpigmentation and freckles. Lumenis M22. How long after IPL can I get a spray tan?

Lasers and sun tanning don't mix, but it sounds like you already know this. Just to reiterate though, this is because sun exposure after laser treatments can result in skin damage, scarring, or hyperpigmentation.
In addition, tanned skin responds differently than untanned skin to laser treatments. Spray tans are just chemical sprays that react with epidermal cells to produce a brown color change. If you have IPL treatments after getting a spray tan, it can be problematic. The laser energy can be absorbed by this superficial tanning spray pigment rather than the intended target of the laser. This can cause burns or ineffective treatment. So you should certainly not get a spray tan if you are going to have further IPL treatments.
Finally, if no further IPL or other laser treatments are planned, then it's a slightly different story. Once the  skin has healed from the laser, spray tanning should be quite safe. IPL generally doesn't cause significant skin injury like blistering, so waiting about a week after IPL to get a spray tan should be adequate for safety. On the other hand, if you have any open wounds, blisters, or peeling, you should wait to have a spray tan until these are fully healed. This will avoid adverse skin reactions and uneven tanning.
Hope this was helpful to you, and good luck!

I recommend not tanning nor using spray tans after having your IPL treatments. If you are not done your treatments which are usually 3-4 weeks apart for at least 4 sessions, I definitely would avoid the sun and the spray tans.  If you have a spray tan, you cannot have another IPL till the spray tan is gone. Otherwise the pigment from the spray tan will absorb the laser energy and put you at risk of a skin burn.

If you completed a series of treatments for hyperpigmentaion, my answer to you is "never". The pigments from the tanning will be absorbed by your skin and could bring back some of your pigments. Also do not underestimate that breathing in the tanning product is an irritant to your lungs.