There is no obligation to have the case heard in the district court within six months (Bond-007). Many cases take a lot lot longer than six months from the date of the alleged offence to conclusion. However, the complainant Garda usually must make a complaint(i.e. particulars of the alleged offence) to the district court office within six months of the alleged offence. The actual court date can, and usually is outside the six month period.
To be honest, the vast majority of these types of fixed penalty offences which are not paid will result in a summons, so I think you must expect to have to appear in the district court. There is the very real prospect that the garda will not appear in the DC, in which case you can ask the judge to strike the matter out, although judges seem increasingly willing to adjourn the matter to a later date, if it is another no show than you ask again for the matter to be struck out and that should be the end of it.
If the garda bothers to turn up at court, and you contest the offence, then it is quite difficult to predict the outcome. District Judges are notoriously whimsical, while you probably have an arguable case, you should definitely bring along the witnesses and hope for the best. There really are no guarantees. Good luck.