Timmers qualified for three swimming events at the 2012 Summer Olympics in London, by clearing a FINA B-standard entry time of 48.92 (100 m freestyle) from the Belgian Championships in Antwerp, just a 0.10-second deficit from an A-cut and a Belgian record held by Yoris Grandjean. He also teamed up with Dieter Dekoninck, Emmanuel Vanluchene, and Jasper Aerents in the 4 × 100 m freestyle relay. Swimming the anchor leg, Timmers recorded a fastest split of 48.18, but the Belgian team rounded out the finale to last place in 3:14.40.