в кратчайшие сроки

on an urgent basis (ABelonogov); as soon as possible (bookworm); within the shortest possible period of time (ABelonogov); in a short time frame (Manufacturers want to solve a specific problem by implementing a small project in a short time frame. Andrey Truhachev); in the shortest time possible (Andrey Truhachev); in next to no time (immortalms); as soon as practically possible (nerzig); as quickly as possible (Alex_Odeychuk); in no time (bolton926); within a very short time (Andrey Truhachev); on short order ("We don't know whether President Putin has made the decision to invade. We do know that he is putting in place the capacity to do so on short order should he so decide," Blinken told reporters in Europe a day before meeting Russian Foreign Minister Sergei Lavrov. "We must prepare for all contingencies."

washingtonpost.com 4uzhoj); promptly (gennier); as promptly as possible (Johnny Bravo); within as short a time as possible (emirates42); as soon as possible (If you do something as soon as possible, you do it as quickly as you can: We need the repairs done as soon as possible. CALD Alexander Demidov)

at your earliest convenience (более вежливая форма 4uzhoj)

at a moment's notice (CNN, 2021 Alex_Odeychuk)