How should I use it before self-tanning, given that the formula contains oils?

Pre-tan preparation is one of the intended uses of this scrub, and the logic is simple: self-tanner develops on the outermost skin cells, so if those cells are flaky and uneven, the colour turns patchy and fades unevenly. Polishing with the sugar–salt–coffee base evens out that surface so the tan goes on smoothly.

The one thing to manage is the oil-rich texture. The plant oils that make this scrub comfortable to use can interfere with self-tanner if they are still sitting on the skin, because a film of oil acts as a partial barrier between the product and the skin. Practical approach:

• Exfoliate the day before or at least several hours before applying self-tan, not immediately before. This gives the skin time to settle and any residual film to absorb.
• Rinse very thoroughly after scrubbing, especially on areas where tanner tends to grab — knees, elbows, ankles.
• Skip heavy body creams between scrubbing and tanning; the conditioning left by the scrub itself is usually enough, which is convenient here since over-moisturised skin can also dilute tan development.
• Pay extra scrubbing attention to rough zones (knees, elbows, heels), as these are exactly where self-tan otherwise darkens too much.

Done this way, you get the two things that matter most for an even self-tan: a smooth, uniform surface and clean, residue-free skin at the moment of application.