When were they reared? If last year, too early unless these colonies are boiling over and stinging en mass. If that's the case just nip and unite. If 2019, you have had a year to assess good or bad so if you feel their temperament doesn't meet criteria, nip and unite.
How many queens are you rearing from and have they proven their worth over at least two seasons? One season really isn't enough IMO but I will make exceptions. In the case where the queen has proved exceptional for two or three seasons and her daughters and grand daughters are following suit, I would have no problem with using the youngest. We have three queens who fit this category with up to four generations of offspring queens. Two of these fourth generation queens are on the cards as possibilities this year. One of them was the result of an apiary vicinty mating at the end of August last year. Queen seen and BIAS on September 15th, they are looking well and still have stores, gorgeous little black bees.
I'm hoping the old girls are still around, especially 'Lagertha'. She was the first to reach 'exceptional' status and has maintained those high marks, producing over a hundred pounds of honey last year in her fourth season and a colony that never seems to stop flying.
I will shed a tear when she goes