The source explicitly advises extra caution if you’ve recently used other strong chemical hair treatments. Perms, relaxers, Japanese straightening, and keratin smoothing treatments all alter the hair’s disulfide bonds and cuticle structure, making it significantly more porous and reactive to oxidative dyes.
Standard professional guidance is to wait a minimum of 14 days after a perm or relaxer before applying permanent color. This allows the hair’s pH to stabilize and the cuticle to partially recover. Even then, do a strand test: mix a small amount of color and developer, apply to a few hidden hairs, process for the full time, rinse, and evaluate. Over-porous hair may grab the ash tone (the .1 in 7.31) too strongly, turning greenish or muddy, or the color may develop much faster than the stated time.
If the strand test shows uneven uptake or excessive damage, consider a semi-permanent or demi-permanent toner instead, which deposits without ammonia and is gentler on compromised hair. The included keratin balm will help condition afterward, but it cannot reverse structural damage from overlapping chemical services.