Forget it.

Try to use the longest interest-free period of the two cards;

Card A will start consumption on the 3rd, for example, consumption on March 3rd, billing on April 2nd, and final repayment Date: April 21st;

Card B will start consumption on April 9th, and cash can be withdrawn or cashed out on April 20th to return card A.

Card B will issue the bill on May 8th, and the repayment date will be May 27th; Card A will withdraw cash on May 25th and 26th to repay card B.