Are Old Testament saints resurrected at the same time as the rapture of the church?
Old Testament saints are not resurrected at the same time as the rapture of the church. They are part of a separate group, the gleanings and corners, resurrected at a slightly different time. Daniel specifies this resurrection, which also includes the tribulation saints. They are not in the body of Christ, so they are resurrected separately.
Les explains that the resurrection has an order: Christ the firstfruits, afterward those who are Christ's—the main harvest, the body of Christ—and then the end. He then turns to Daniel chapter 12, where a third group is pictured by the corners and gleanings. These are not as numerous as the main harvest and are resurrected at a time slightly different from the rapture of the church. This group includes Old Testament believers and tribulation saints. The tribulation saints are saved during the seven years through the preaching of the 144,000 Jews, 12,000 from each tribe, but they are not in the body of Christ, so their resurrection is separate.