The leaf damage is not associated with any water or heat issues. It looks to be mechanical rather than pathogenic and could have been caused by rough handling, transport or possibly an insect.

All the trees need at this point in time is proper watering. Long and slow but infrequently. That 3rd day frequency sounds reasonable but you really want to check the soil surrounding the rootball and determine from that when to water rather than relying on any sort of schedule.

Thanks ! If it was mechanical, wouldn't the whole leaf dry out as opposed to starting from the tip and work onwards.. especially this picture .. see below.

Thanks again for your help !!