Hi My Sister Has To Have Two Stents Placed Into

Hi my sister has to have two stents placed into her heart artery. She was told part was blocked 100% and in another area of the same artery it is blocked 70%. How long should she wait to have this done? She has not had a heart attack. She had pain in her chest twice and felt sick after the second pain she saw her heart doctor and they said tey could posssibly wait till January to do the procedure. That sounds to long to wait to me.