Sitting Unsupported

Hi mamas! My sweet boy will be 5 months in just a few short days, and I’m really hoping to get him to sit unsupported by 6 months so we can start BLW. He loves sitting and leaning back against me, but the second I lean him forward and try to get him to support himself on his hands he leans right back onto me. I know every baby is different and reaches this milestone at different times, but does anyone have any tips on getting him to be more interested in doing it on his own?