Trapping 2 strays + kittens

Hello everyone. My first thread was about 1 of the 2 stray cats i trapped in mid May. I was able to locate the owners of one but the 2nd has not been claimed and the vet said shes about 6 1/2 weeks or so pregnant.
Today while in my back yard i spotted 2 more strays walking into a wooded area next too my house. I noticed that both have swollen abdomens. I continued to watch where they went. Looks like they were going back to their kittens. I was only able to make out 3 kittens but there might be more. I have already returned the traps to the humane society but the weather right now is nasty. Its cold and rainy.
Should i attempt to catch the kittens now then set up traps tomorrow for the 2 females? Should i wait and try to trap them all together? Does anyone have any advice? I just hate seeing them out there in this nasty weather.

I forgot to mention that from what i can see, the kittens look to be between 4-6 weeks old

If the kittens are 4-6 weeks, they shouldn't be hard to trap. I doubt you'll be able to catch them - their mothers have taught them to run from predators (which we look like when we're swooping down on them).  I would try to determine how many there are, then set the traps accordingly.  You don't want to miss any kittens but remember, they have been taught to hide.

I trapped a cat in the woods behind my house once without knowing she had kittens.  Three days later, I heard a rustling sound and saw two kittens, about six weeks old, in the shrubbery.  Needless to say, it was very easy to catch them.  I set up a crate and tied a length of twine to the door, then looped the twine through the side of the crate.  I wound the twine back to my house (about 25 feet) and put a plate of food in the crate with the door open.

Within minutes, FOUR kittens were eating.  I pulled the twine and closed the door.  I only wish it was that easy every time I trapped!  I checked the woods for several days and set the crate up again two days in a row but I got them all.

Good luck and thanks for helping them all.

Thank you for the advice. My friend is going to take me to get traps this afternoon. Hopefully it works again. Would hate for those babies and mommys to be stuck outside in this weather