In James Blish's Welcome To Mars (London, 1978), as soon as Dolph Haertel realises that he is stranded on Mars, he makes an inventory of all his resources, in Chapter 4.
(I am summarising this to confirm that it holds together.)
Oxygen: "He had started with five flasks, totalling...45 gallons..." (p. 42) One is probably almost empty after the journey (three days?) and less than one day on Mars. Dolph can leave his hut wearing respirator and goggles.
Water: "...three 17.5 gallon drums..." (p. 42). He would need to drink at least a gallon a day and would lose a gallon through evaporation.
Food: Two weeks' supply of K rations.
Power: Rechargeable batteries. Power needed for air pressure and heat and to electrolyze water (if found) for oxygen.
On his first full day on Mars, in Chapter 5, called "Morning on Mars," he:
locates and closes leaks;
makes an electric motor from metal and wire;
uses Sterno and blowpipe to make a pump from glass tubes and nails;
pumps Martian air into his hut so that he can slow the rate of oxygen use;
plans to build a generator with a magnetized steel rotor and to make windmill sails from canvas;
finds water in some of the Martian lichen sacs.
After this, I find that the chronology becomes uncertain. Chapter 6 is called "Evening on Mars" and seems to follow directly after Chapter 5. Nanette follows Dolph to Mars, with little delay it seems. Meanwhile, Dolph makes a wine press, uses lichen sap to keep his air moist and discovers that the apparently empty sacs contain oxygen. Collecting more lichen, he sees Nanette arrive.
Chapter 7 changes the scene to Earth where twenty nine days pass, after which it is believed that "the children" cannot still be alive on Mars. The chapter ends with Dolph rescuing Nanette from the wreck of her ship with the implication that he is doing this after the twenty nine days have elapsed. Chapter 8 confirms that he has been on Mars for weeks although he had only had two weeks of K rations and has not yet experimented with Martian food sources.
In any case, Nanette brings fresh supplies. Dolph goes on to learn that Martian lichen is not only edible but also slows the metabolism, thus reducing breathing, and he mines water.