As a lead vocalist, it is up to you to know the song well so you can carry it. Waiting for your music and being unsure of your entrances will cause the song to lag and the energy will fall flat; you need to set the pace and energy of the piece. Actually, a strong singer really doesn’t need any music at all and is fully confident singing a capella.
Next time you are singing lead, decide in advance that the band is following you, not the other way around. You will be surprised at what a difference it will make in the feel and energy of your song.