peace glo,

it's good to see you reaching out to your neighbor like that. Islam encourages very strongly on treating neighbors well and the angel Gabriel emphasized on the rights of the neighbors that the prophet (saws) said he thought he would have to include them in his inheritance. Our neighbors are very special and we should always treat them well, regardless of faith or what not.

It would be best to give it on Thursday. If eid falls on friday then you're safe and if on saturday then they'll still be happy to get the presents a day ahead.

As for what to give. Kids normally like to collect money from all the adult family, relatives, family friends, etc and then they go buy what they like. Several good ideas have been given here. You can give money in an envelop with Eid Mubarak on top of it or something else. Since you mentioned the family is a bit poor, it would be better to give them gift voucher/card or something to a place with many options (walmart maybe?) and they can buy what they need. Sweets from local arab/paki store is good also. And if the mother wears the headscarf maybe you can look at local arab store to see if you can get one for nice deal. Just some suggestions, i'm sure you'll think of something they could really use.