Its normaly fine to wait till the top few inches are dry, and then soak the pot till saturated with citrus feed/water, it is best to under water than overwater, if it now is very dry and now going imp then i would water it, but make sure you let it dry out well afterwards as it may have been overwatered before you got it so may have damaged roots, if the roots are damaged it will show up as needing water as they can not take in water, so you need to underwater till it recovers,
check the drainage on the pot is good , as you may have very wet compost at the bottom of the roots causing problems, see if you can lift the plant out of the pit to have a look at the bottom of the roots , check there dryish and not brownmushy or very smelly

a common problem is that the plant when bought needs repotting, not so much in a bigger pot, but to replace the soil based mix with a faster draining non compacted new mix of something liek 50/50 perlite/lime free compost or 50/50 bark chips/sphagnum moss etc, check there are enough drainage holes in the pot, and that the pot is lifted a bit off the floor and not in a saucer to collect water, it needs to drain quickly and all water not to touch the bottom of the pots
if you go for a larger pot, if the plant is rootbound, only go slightly bigger a few inches at most as having too big a pot is a usual cause of a pant dieing due to the wet area that will build up outside of the root area

Im not sure how hot it gets over there, but citrus dont need full sun, and as its never that hot here ( in the UK ) mine wilt if they get a realy hot day with direct sun as they are not used to it, i have heard that in the states many people cover young trees with a shade cloth to get them used to the direct sun/heat if they have been indoors/undercover at a nursery

Its always best as well if the leaves are curling to have a good look that theres no pests on the plant such as spidermites or scale, just to check

Interesting Starloc. Citrus here thrive in full sun! They grow like weeds everywhere! Fruit is free on any street here because it drops everywhere in Jan-Feb. Too much of it! If I have a problem with mine, I take a leaf to a reputable nursery, show it to them, and they always solve my problem. My worst case is "thripes." But I use that Bayer Systemic to fix that. I have some in containers, and some in the ground. Ground works best, and I have overwatered my containers on occasion. I got this cool tool which prevents me from doing that ever again. Google "soil sleuth." It's cheap and does the job! Nice little soil detective!
Good luck to you!
Suzi