We know Jesus Olivet prophecy (synoptic) reaches beyond the first century because the conditions (e.g. 'worst tribulation ever, nor will occur again'; as well as Jesus' 2 nd arrival where 'the entire world will see him.' Mt 24:30; Rv 1:7 didn't happen in the 1 st century as well as some of the Scripture precursor particulars below.
Mt 24 YLT
3 And when he is sitting on the mount of the Olives, the disciples came near to him by himself, saying, 'Tell us, when shall these be? and what is the sign of thy presence, and of the full end of the age?'
7 'For nation shall rise against nation, and kingdom against kingdom, and there shall be famines, and pestilences, and earthquakes, in divers places;
8 Yet all these are the beginning of pangs. CLV
21 for there shall be then great tribulation, such as was not from the beginning of the world till now, no, nor may be.
30 and then shall appear the sign of the Son of Man in the heaven; and then shall all the tribes of the earth smite the breast, and they shall see the Son of Man coming upon the clouds of the heaven, with power and much glory;
34 Verily I say to you, this generation may not pass away till all these may come to pass.
37 and as the days of Noah--so shall be also the presence of the Son of Man;
45 'Who, then, is the servant, faithful and wise, whom his lord did set over his household, to give them the nourishment in season?
48 'And, if that evil servant may say in his heart, My Lord doth delay to come,
49 and may begin to beat the fellow-servants, and to eat and to drink with the drunken,
Mk 13 AV
8 For nation will rise up against nation, and kingdom against kingdom; there will be earthquakes in various places; there will also be famines. These things are merely the beginning of birth pangs.
19 For those days will be a time of tribulation such as has not occurred since the beginning of the creation which God created until now, and never will.
Lu 21 NASB
10 Nation will rise against nation and kingdom against kingdom,
11 and there will be great earthquakes, and in various places plagues and famines; and there will be terrors and great signs from heaven.
25 There will be signs in sun and moon and stars, and on the earth dismay among nations, in perplexity at the roaring of the sea and the waves,
26 men fainting from fear and the expectation of the things which are coming upon the world; for the powers of the heavens will be shaken men fainting from fear and the expectation of the things which are coming upon the world; for the powers of the heavens will be shaken.
32 "Truly I say to you, this generation will not pass away until all things take place.
IMO nations and kingdoms WWI & WWII , "pangs" woe , Noah's day echo violence, Atheism, 100 yrs , the "evil slave" Mt 24:48-49 and the sharp contrast between the "wicked and wise" Dn 12:10 lead me to believe Mt 24, Lu 21 and Mk 12 ultimate projection is the 21 st century. I live my life accordingly. The JW iteration is part of the "evil slave" event. Those who separate themselves from this "evil" element and diligently seek Biblical truth are aligned as with the "faithful." Because of computers networked around the world, diligence makes Biblical truth available to everyone "faithful."
Jesus began ruling after his resurrection in the 1 st century. But his second arrival is as explained above, I believe.