Delaying Chemo

I have HER2 Pos breast cancer that was in the duct; Grade 3, but ER Negative.

Cancer was just 10mm and Lymph Node biopsy was clear.  So I consider myself fortunate they found it early.

I had a re-excision early June due to them finding disease at the edge of the margins and then a delay due to Drs strike I suspect.

Next steps will be 6 rounds of Chemo, radiotherapy then other therapies; but we are due to go to Crete early August for 2 weeks which we haven’t yet cancelled and is all paid for.

Is it safe to delay start of chemo until my return mid August and will that be wise?