Timing for getting pullets? And socialisation questions

This question is as much about my own life cycle as that of the birds

I have decided to purchase 6 - 12 week old pullets rather than chicks or older birds.  My reasoning is that I don't have any room inside the house for raising chicks so I need chickens that can go outdoors right away (also no electricity in the coop).  But I also want to 'bond' with them and socialise them myself so don't want adult hens.

I can have up to six birds in my back-yard setup and I am hoping for a mixed flock of sussex, rhode island red & wyandotte (depending what the breeder has in stock at the time).

I would love to get my flock ASAP but my husband and I will be out of town for three weeks beginning on 1 January. (Note: I am in New Zealand so January = mid summer)

My elderly aunt has offered to look after the chooks while we are away, but I can really only expect her to do the basics like feed & water them.  It wouldn't be fair to expect her to do anything more demanding.

How demanding are young pullets?  For example if I got 6 week olds, had them for a month then left them for three weeks, what demands would they make on Aunty?

Also, what is the ideal time to socialise/train chickens?  By leaving them for three weeks will I have effectively undone any socialisation from the previous month?

By "socialisation" I just mean I want them to be calm around humans, not run away from people but preferably approach them.  I also want to be able to handle them without too much stress for health checks etc.