Practicalities Remember that a guitar is strummed , so a chord will usually be spread across several ticks. At slower tempi a short muted chord might sound better on a single tick, but this is the exception rather than the rule. Guitarists don't always strum all six strings, particularly on a fast upward stroke. Leave a 'gap' of one or two ticks to prevent retriggering.
Guitarists usually start a downward stroke early so that the top string plays on the beat.
So the first 'chord' of the bar might start around 5 ticks before the bar. An upward stroke usually starts roughly on the beat. There are a great many ways to 'voice' a single chord on guitar, so whichever voicing you choose will nearly always be possible, if not actually easy. It is sometimes necessary or desirable to use a believable voicing, so it's useful to know the tuning of the strings. Alternatively try using a separate short note for each fret, for a more realistic sound.