Such a case can be recognized, either from a general knowledge of the location of the constellations at various seasons, or with the aid of the Nautical Almanac, where at the beginning of each set of monthly tables in the calendar the sun's right ascension and declination will be found.

In locating the sun, if you find that its right ascension differs by less than an hour, one way or the other, from that of the planet sought, it is useless to look for the latter.

If the planet is situated west of the sun--to the right on the chart--then it is to be looked for in the east before sunrise.

But if it is east of the sun--to the left on the chart--then you must seek it in the west after sunset.
For instance, I look for the planet Mercury on October 12, 1901.

I find its R.A.to be 14 h.