how early can we take blood test?

CD 26, 11 DPO n cycle day length is 30 days... ovulated around 31 may- 1st june... BD'd every alternate day during fertile period.. my body z gone bonkers since a week..😑

AF is due in 4 or 5 days!! i feel i should better invest in blood work than investing in test kits🤨😐😐