‘Tribulation saints’ is somewhat speculative. Does it refer to a group unsaved folk, the left behind but repentant when the sky starts falling? How did they avoid the grand delusion? Some would argue that the passage in Rev. 7:14 is in reference to ALL of the saints who’ve suffered immense persecution over the past 2000 years for the cause of the Gospel and not just some speculative group of Great Tribulation martyrs. Wouldn’t the extremely persecuted and martyred Christian over the last 2000 years be included in any group of Christian martyrs? IF that is the case, then they are there standing before the throne of God AFTER the rapture has occurred. How else could they be standing before the throne of God unless they have been taken-up and changed?
Rev 7:14 KJV -  And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.
Did they come out of thee final Great Tribulation, or out of immense persecutions throughout the Church-age?
Others have used the passage to support a post-Great Tribulation, a multi-rapture OR a even a mid-Tribulation rapture.
These are the sort of ‘hard sayings’ that make it rather difficult to be dogmatic about the nature and timing of the rapture, wouldn’t you agree?
It’s just a feeling, not necessarily based in any certain Scripture, but I tend to think we Christians may have to endure the opening ‘warm-up’ days of the final Tribulation period, snatched away at the final moment before all heck breaks loose on earth. We should at least be prepared for the possibility. I could be wrong though.