there is no way to accelerate the curing of liquid cement. Liquid cement 'welds' the two pieces of plastic together, basically forming one piece. The liquid cement will melt the two surfaces it's applied to, and when they are pressed together, the welding will begin. To ensure you get enough of the cement in the seem, hold the pieces together, allowing a small gap between the two (fraction of a millimeter). Apply the liquid cement to the entire gap, wait a second, then squeeze the gap together and hold - either apply pressure with your hands, rubber bands, or some sort of weights (books, etc). I never heard of waiting 24 hours to let the bond cure - you should be able to go back in an hour and be able to start sanding...
