Correct

先是

/ xiān shì /
Strokes

Example

As a Conjunction

before

1
xiānshì
先是
xìn
  
,
ér
继而
yuè
喜悦
  

My initial disbelief was replaced by delight.

2
xiānshì
先是
wánchéng
完成
le
zuò
作业
  
,
jiēzhāo
接着
yòu
kāishǐ
开始
shū
读书
  

She finished her homework and then she started reading.

3
xiānshì
先是
tóng
同意
  
,
hòu
yòu
fǎnduì
反对
  

Originally, he agreed, but later he disagreed.

As a Conjunction

before this/that/then

4
Xiānshì
先是
  
,
jiào
le
nián
shū
  

Before that/this/then, I worked as a teacher for a year.