"Ryan's in the best state of them all, then Stephen and then Gethin. They're all progressing well and, hopefully, they're going to be fit for selection, if not for this game then definitely for the second game," said Gatland.
All three are suffering from calf muscle problems and the target for everyone is to be available for the game against Samoa on 18 September. Jenkins hasn't played since January after having an operation on his toe and then picking up a calf strain.
Stephen Jones won his 100th cap against the Barbarians in June, but then sat out the three warm-up matches against England (2) and Argentina. Ryan Jones played against England, but missed the game against the Pumas as a precaution.
"Ryan's confident that he can take a full part in training. Stephen might be one or two days, but we're taking Gethin a little bit slower," added Gatland.