Gaj Kesari Yoga, a very lucky planetary combination is caused when Jupiter is in Kendra (that is in 1st, 4th, 7th or 10th house) from the Ascendant or the Moon. Jupiter is the planet of growth and wealth, and Moon is the giver of happiness and stability of wealth. This yoga bestows one with sharp intellect and much prosperity and one will be loved and respected by people around.

This Yoga is really effective and auspicious when Jupiter is not afflicted due to either retrogression or debilitation or being present at the junction of two signs or due to aspect of any malefic effect of planet in the birth chart. Similar conditions will also apply to Moon in birth chart [except the point of being in retrogression].
When no affliction to Jupiter or to Moon is present, Gaj Kesari gets its full power and offers abundant wealth and fame to a native having such a clear yoga.
General effects of Gaj Kesari Yoga:

The fundamental effects of this yoga is very high clarity, impartiality and goodness of intellect, polite and generous attitude, power and capacity to make others grow in life, while one enjoys for himself much wealth, power, popularity and respect.

This Yoga helps you get a long life prosperity, virtue, leadership qualities, friendly attitude, generosity, politeness and overall distinction in life.

How Gaj Kesari Yoga is formed in your chart:

[Also the strength of the yoga]
Gaj Kesari Yoga is very actively present in your birth chart since your Jupiter [in Libra] is in the 4th house from your Moon sign in Cancer.
Moon is very strong with very high Shadbala with nearly 100% digbala [directional strength] and also much auspiciousness.
Jupiter too is quite strong but possesses rather low directional strength [digbala] and auspiciousness.
Also Jupiter is placed at the center of the nodal axis.
However Jupiter possesses quite high residential strength.
Thus overall strength of the yoga will be around 75% but it will be much more effective during dasa - the main and sub periods of Moon [as compared to the periods of Jupiter].
Time periods when Gaj Kesari Yoga would turn effective:

The main and sub periods of Jupiter and of Moon will offer the good effects of this Yoga.
The main period of Jupiter for you will start around your 75th year and hence the good effects will be less useful.
The main period of Moon will operate from 23 Mar 2019 to 21 Mar 2029 [10 years] and will offer full effects of this yoga.
This will be during a highly mature but yet very energetic stage of your life [38 to 48 years].
During these ten years, you will be able to make full use of this yoga and achieve all the good results.
Within this long period of Moon mahadasa or main period, the sub periods of Moon and Jupiter will offer you especially increased benefits.
These sub periods are 23 Mar 2019 to 20 Jan 2020 and 20 Feb 2022 to 21 Jun 2023.
During the other main periods of your life, the following slots of time will offer the results of this Yoga.
06 Sep 2030 to 11 Aug 2031, 22 Aug 2035 to 21 Mar 2036, 03 Dec 2038 to 26 Apr 2041, 03 Sep 2051 to 02 Mar 2053.
Suggestions on how to improve the results:

The basic premise of this yoga is clarity and focus of thoughts on doing well for and to others.
Thus you will do well to act in virtuous, well meaning and inclusive manner.
Welfare of others should be the priority and this will bring benefits for you as a corollary.
Trust the almighty to guide you while you should abhor any shortcut to make personal gains.
Such efforts should be consistent and free from any optimization or rationalization.
Precautions, if any:

Avoid over dependence on the yoga and attach priority to hard work and sincerity.
Do not wait for a good period to arrive till you start trying to do well to others or for you.
Follow the significations of Jupiter and Moon and take only fair actions with a stable mind.
Under no situation make any compromise on your efforts or their rightfulness.

Special remedies to increase the good effect:

Worship Lord Siva, every day.
Chant “Om Namah Sivaya” as frequently as possible, the more the better.
Even silent chanting will do.
Chanting of this mantra will usher in the blessings of Jupiter as well as of Moon.
Avoid any wrong or unfair action, especially on Mondays and Thursdays.