Agree on the actual entrance
Before counting, identify the first sound each person makes. The singer may begin before the first full bar, while the instrument enters later. Look at the opening lyrics and chords, then confirm the entrance by listening rather than assuming the first displayed word falls on beat one. Say where the pickup begins in the count. If the arrangement opens with a free vocal phrase, agree on the visual or musical cue that starts the accompaniment instead. A count-in only helps when everyone understands the point it is counting toward.
Make the count sound like the song
Tap the pulse for a few seconds before speaking. Count at the intended tempo with the same subdivision you feel in the opening, using a clear and comfortable voice. For a straightforward four-beat bar, try one full bar of preparation and one full bar before entry. Change that plan when the meter or pickup requires it. Have the group clap the entrance without instruments first. If the claps disagree, resolve the count before adding chord shapes, melody, and device navigation. Volume alone cannot fix an unclear rhythmic instruction.
Practice starts as their own task
Run the count-in and first two phrases, stop intentionally, and reset. Repeat three times with a different person leading once. Check whether the first chord lands consistently and whether the singer has enough breathing time. Open the song display before giving the count so nobody is searching for a page during the final beat. For playback practice, follow the recording's established timing; a spoken count does not make the player automatically start on your cue. Finish by starting from silence without extra discussion. Record the agreed opening in your rehearsal notes so the next session begins with the same plan.
For an opening with several silent beats, continue a small visible pulse after the spoken count. Remove that extra help later if it is unnecessary, but keep the entrance unambiguous while learning.