better to just take classes if full-timer?

[Merlin]

If you don't have any certs or credits from sophia/straighterline/study.com/etc, and you are going to be a full-time student, is it better to just sign up at WGU and do the classwork there?  

I assume people are getting college credit outside WGU because they are working, and don't have a lot of time to study. If you have all day to do WGU work, is it better to just get the credits at WGU?

Well, time-wise, you can complete courses at WGU in roughly the same time that it takes to complete them using alternative credit providers like Study.com, Straighterline, or Sophia. So if you're looking to save time, it is a wash either way.

If cost is a concern, you can generally complete courses cheaper via alternative credit providers, but you cannot use financial aid to pay for them

If you think you may consider looking at earning another degree after completing a WGU bachelor's degree, you may be better off taking the lion's share of courses directly from WGU. ACE credit courses are not accepted everywhere, so if you apply to any other school for a second degree, that school will also need to accept ACE credits in order for them to be considered as part of your application. This can be a big deal if you want to attend a ranked university for grad school as you may have trouble meeting entrance requirements if your core courses include a lot of ACE credits.

So the answer is, it depends on what you want to do.

Can you transfer credits to WGU after you have already started at WGU? For example, you might want to take English at Sophia instead of WGU, after you already started at WGU.

I'm pretty sure that WGU is a school where you have to transfer in everything you want to transfer in before starting your degree.

To confirm, WGU requires that any courses you wish to transfer in have been received and evaluated no later than the 15th of the month before the start of your first term to be considered. They will not accept any additional courses that arrive after that date without prior approval, and even with permission, those credits would still need to be evaluated before the first day of your term to be considered.

Technically you could withdraw from the school and apply again later after transferring in the credits, but that creates other problems so it isn't recommended.