Rev 6: 9 when he had opened the fifth seal, I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held: 10 And they cried with a loud voice, saying, How long, O Lord, holy and true, dost thou not judge and avenge our blood on them that dwell on the earth?
11 And white robes were given unto every one of them; and it was said unto them, that they should rest yet for a little season, until their fellowservants (Prophets) also and their brethren, that should be killed as they were, should be fulfilled.

When we get to the Fifth Seal, there’s no beast, no living creature. Now notice he (Jesus)had opened the fifth seal, I saw under the altar. When the Fifth Seal being opened, the Church is gone

These now, souls under the altar for the Word of God and the testimony they held for being God’s people, the Jews.
The grace of God comes to them, and Jesus gives them each one a white robe plumb over after the Church is gone.

The Jews under the altar did not have white Robe during the Grace Age because, to have White robes one Must accept Jesus Christ first.
These souls under the altar only get White Robes once Jesus is recognized at the Start of the 70th Week of Daniel.

Now from the beginning of the week of Daniel, Jesus said – to wait a “Little Season” Till fellow brethren is Kill,
which is about 3.5 to 4 years when the Antichrist goes to kill the 2 Prophets and the Jews remaining in the Land of Israel.

Therefore a Little Season is lest than 10 years or a Decade.