Please check with your production if can do inspection for this order on 20th Oct. afternoon,
(这句比较清楚的知道,如果可以的话,安排10月20号下午验货)
if can do please contact Eric by the phone since 21st Oct. the QCs are fully arranged.
(但是这句,怎么又出现一个10月21号呢,这里since起了一个什么的意思呢)
最近QC验货紧张,很难订,都赶在圣诞节前到货。
This sentence means that the quality control department is currently very busy and it is difficult to book their services. They are trying to ensure that all inspections are completed before Christmas.
In the previous sentence, "since" means "starting from." So, the sentence means that starting from 21st October, the QCs will be fully arranged, so if the production team can arrange inspection on 20th October afternoon, they should contact Eric by phone.