Question: How long does it take to create a Pure Land?
Answer: A sample answer can be found in the Immeasurable Life Sūtra《无量寿经》, by looking at how long it took to create Amitābha Buddha’s (阿弥陀佛) Pure Land, which is the most renown Pure Land.
 First to note is that it is not recorded in the sūtra, on how long it took for Dharma Treasury (Dharmākara) Bodhisattva (法藏菩萨) to practise the Dharma in previous lives, to karmically deserve encountering of King Of World With Ease Buddha (世自在王佛), from whom he learnt the key lessons on how to create an ideal Pure Land. Surely, it would have taken a very long time.
 Second to note is that it is not recorded in the sūtra, on how long it took for King Of World With Ease Buddha to show and teach Dharma Treasury Bodhisattva the nature of ‘two hundred and ten koṭīs of all Buddha lands, their heavenly and human beings’ good and evil, with the coarseness and subtle wonders of their lands,’ (二百一十亿诸佛刹土，天人之善恶，国土之粗妙) and how they are adorned. (With 1 koṭī being about 10 million, 210 koṭīs is 2,100 million.) According to the sūtra, ‘That Buddha’s lifespan, was forty-two kalpas.’ (其佛寿命，四十二劫。)
 Third to note is that after Dharma Treasury Bodhisattva heard and saw the above, ‘For five complete [great] kalpas [i.e. world cycles, of about 1.344 trillion years each], he contemplated on gathering and receiving the pure practices of adorning Buddha lands.’ (具足五劫，思惟摄取庄严佛国清净之行。)
[It should be noted that after such a detailed preview of so many (pure and defiled) Buddha lands, it takes such a long time to review them, so as to synergise, for maximising their advantages, and for minimising their disadvantages. If without such a preview and review, it will surely take a much longer time to learn how to give rise to complete vows for shaping an ideal Pure Land.]
 Fourth to note is that after Dharma Treasury Bodhisattva proclaimed his 48 great vows before King Of World With Ease Buddha, which include those on the nature of his Pure Land, ‘he wholeheartedly focused on his aspirations to adorn a wonderful land.’ (一向专志庄严妙土。所修佛国) As for how long this is, this is stated – ‘For an inconceivable period of extremely many distant kalpas, he accumulated and planted Bodhisattvas’ immeasurable virtues and practices.’ (于不可思议兆载永劫，积植菩萨无量德行。)
To sum it up, the time spent to create his Pure Land comprises of  one very long undetermined period, added with  another undetermined period, added with  five kalpas, which is 6.72 trillion years, added with  an extremely long period. It is most noteworthy that the last period  alone was so inconceivably long, that there was no astronomical number of kalpas stated.
For this, we should be immeasurably grateful to Amitābha Buddha. Appreciating his tremendous efforts, that even big numbers cannot fully quantify, and that many words cannot fully describe, we should all aspire to reach his Pure Land, so as to not let him down, to most swiftly expedite our progress and that of others towards Buddhahood and creation of more Pure Lands. Doing so, we will be able to more efficiently guide those we have great karmic affinities with.
How To Create A Pure Land As Quickly As Possible?