the problem is that the few weeks immediately after a tank is cycled is quite fragile, you often get an unexplained bit of bacteria die off and a blip in your readings or something like that. thats why we advise to do a qualifying week. it's basically all risk mitigation, if you wait the extra week before adding fish you have much less chance of having a blip in your readings and accidentally exposing your fish to ammonia which would be such a shame after all your hard work.
either way you run a risk here, you either risk your dad getting something wrong and messing up the cycle or you risk something going wrong with the water levels and it going undetected because your not there to monitor it.
so (in work mode now) you need to do a risk assesment and see which course of action you feel would be worse.
so lets take option 1 - put some fish in and leave your dad to look after the tank,
can your dad be trusted to test the water every day?
will he be able to do a several daily water changes if the readings are not what they should be?
can you be sure he won't do something like overfeed the fish and cause a mini cycle?
if he does make a mistake the conseuqnces of the action are very high, you could kill or cause permanent damage to your new fishies. however if he gets it right and there's no blips in the readings then it could all go fine.
option 2 - get your dad to add ammonia for you
again can he be trusted to test and add ammonia every day?
the most likely problem is either a pH crash or he adds too much ammonia and stalls the cycle. if he does either of these and the cycle is then stalled for all 5 days (worst case scenario) then what you'd have to do when you come back is water changes and sort it out. once you'd fixed whatever stalled the cycle you'd find that the bacteria colony is mostly still there, you may have to do anoter week of cycling but it's highly unlikely that you'd be back to square one. also remember while the consequences might be a pain in the butt for you, there's no real risk involved, no animals will get harmed.
so my choice would be option 2, just get him to add 2/3ppm of ammonia each day which is much less likely to cause the pH to crash and also less likely to overdose as even if he adds double what he's meant to it'll be fine. if everything goes smoothly while you're away then you will jsut need 1/2 days o working it back up to 5ppm of ammonia a day, then a qualifying week at this level and then you can add fish.
