J.S.
Don't do anything dangerous like drinking castor oil. All that will do is give you and your baby inside you diarrhea, and it will severely dehydrate you. It's very dangerous stuff.
Honestly, don't "do" anything else to try to bring on labor. Most methods are old wives tales and the rest are really dangerous or ineffective. Just go about your normal weekend and take care of your older child. Remain as active as possible. Take walks. Drink plenty of water. Ask your doctor about anything else.
On Monday, before giving you pitocin or any other medications to induce your doctor can break your water and go from there. The act of breaking your water should be enough to get things going.