Jhana Mastery Of Reflection Meditation

Pa-auk monastery tradition:

If you ask this question at pa-auk, they will recommend "you should in meditation, first". Because mind and minds factor arising are very fast and complex. So, it is not possible for no-attained-jhāna-person to clearly understand jhāna factors. And I am agree with that recommend, too.
This image captured from TEACHING & TRAINING book of Pa-auk monastery:

From path of purification pāli, pathavīkasiṇaniddesa:

ayaṃ panettha atthappakāsanā, paṭhamajjhānato vuṭṭhāya paṭhamaṃ vitakkaṃ āvajjayato bhavaṅgaṃ upacchinditvā uppannāvajjanānantaraṃ vitakkārammaṇāneva cattāri pañca vā javanāni javantiฯ tato dve bhavaṅgāni, tato puna vicārārammaṇaṃ āvajjanaṃ, vuttanayāneva javanānīti evaṃ pañcasu jhānaṅgesu yadā nirantaraṃ cittaṃ pesetuṃ sakkoti, athassa āvajjanavasī siddhā hotiฯ

Translation:

1. Emerges 1st jhāna, then...
2. Bhavaṅga-minds auto arising, break it, then ...
3. Thinking of vitakka by only 4-5 javana-minds arising, then...
4. Agree only 2 bhavaṅga-minds arising, break it, then...
5. Thinking of vicāra by only 4-5 javana-minds arising, then...
6. Loop 4-5 steps by 5 jhāna-elements' sequence, until you will attain Jhana Mastery Of Reflection.

How to notice the Jhana Mastery Of Reflection attainment?

General person use 7 javana-minds arising per thought and uncountable bhavaṅga arising between thought, but the jhāna-master must use lesser javana-minds and lesser bhavaṅga-minds to take mastery jhāna.
The practitioner attained right, exact Jhana Mastery Of Reflection, when he can meditate Jhana Mastery Of Reflection follow above step without any getting struck, such as more than 2 bhavaṅga-minds arising or more than 4-5 javana-minds arising.

Still doubt?

There are many jhāna masters at Pa-Auk Forest Monastery. This is better way, because below quote was written in the path of purification page 94:

So if someone with cankers destroyed is available, that is good. If not, then one should take it from a non-returner, a once-returner, a stream-enterer, an ordinary man who has obtained jhána, one who knows three Piþakas, one who knows two Piþakas, one who knows one Piþaka, in descending order [according as available]. If not even one who knows one Piþaka is available, then it should be taken from one who is familiar with one Collection together with its commentary and one who is himself conscientious. For a teacher such as this, who knows the texts, guards the heritage, and protects the tradition, will follow the teachers’ opinion rather than his own. Hence the Ancient Elders said three times, “One who is conscientious will guard it.”

For alternative translation see:
https://buddhism.stackexchange.com/a/23977/10100
For word definition:

1. http://www.palikanon.com/english/sangaha/chapter_1.htm
2. http://www.palikanon.com/english/sangaha/chapter_2.htm
3. http://www.palikanon.com/english/sangaha/chapter_3.htm
4. http://www.palikanon.com/english/sangaha/chapter_4.htm
5. https://www.accesstoinsight.org/lib/authors/nanamoli/PathofPurification2011.pdf