The general suggestion for zone 8 is around mid February and again in early June using a fertilizer with ratios around 5-1-3 though (you also see 3-1-2, 5-2-3, etc suggested) this is only a rough guide for in ground as it depends on local soil conditions, it also partly depends on the age of the tree.

p.s. over fertilizing Satsumas may cause drop in fruit production

Right now need keep covered with tarp to ground I use metal T post with bucket turn over top to support tarp get long T post tie plant to post not to tight just stop blowing over. Tree take cold but not some Artic Blast we have while young tree. Water soil to keep moist not wet, fresh planted soil loose and want hold moisture well.

Fertilizer with 21 % N after see new growth start with one cup fertilizer at time spread evenly away trunk around plant never apply fertilizer close to trunk tree the N salt kill tree. 3 cups at time during growing season use 2 cup at time next year 2019 and add cup extra every year following. Steering around in garden center you find 21% N Hy Yield has fruit and Nut tree fertilizer may look in more one store to find what tree needs I pick mind up plant farms at Baxley Georgia. I use more than cup fertilizer but put heels to trunk tree fertilize outward one full pint 1 lb. fertilizer I always wet fertilizer into soil stop loosing some laying on top soil mixing into soil work to if wet afterwards here link that help.

https://www.gardenguides.com/112953-care-satsuma-citrus-tree.html