Correct

先是

/ xiān shì / 
Strokes

Example

As a Conjunction

before

1
Wǒ
我
xiānshì
先是
bù
不
xìn
信
  
,
jìér
继而
xǐyuè
喜悦
  
。

My initial disbelief was replaced by delight.

2
Tā
她
xiānshì
先是
wánchéng
完成
le
了
zuòyè
作业
  
,
jiēzhāo
接着
yòu
又
kāishǐ
开始
dúshū
读书
  
。

She finished her homework and then she started reading.

3
Tā
他
xiānshì
先是
tóngyì
同意
  
,
hòu
后
yòu
又
fǎnduì
反对
  
。

Originally, he agreed, but later he disagreed.

As a Conjunction

before this/that/then

4
Xiānshì
先是
  
,
wǒ
我
jiào
教
le
了
yī
一
nián
年
shū
书
  
。

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