= 初めて（です）！
[hajimete (des)!]
if you want to say "It's not my first time"
then it is "初めてじゃない（です）"
[hajimete janai (des)]
----------------------------------------------------
if you want to say "It's my first time to "Verb""
then ↓
日本に初めて来ました
[Nihon ni hajimete ki mashita]
It's my first time to come to Japan
or you could swap
"日本に"[Nihon ni] and "初めて"[hajimete]
初めて日本に来ました
[hajimete Nihon ni ki mashita]
It's my first time to come to Japan
----------------------------------------------------
初めて食べます
[hajimete tabe masu]
It's my first time to eat it
初めて飲みます
[hajimete nomi masu]
It's my first time to drink it
初めて行きます
[hajimete iki masu]
It's my first time to go(there)
初めて見ます
[hajimete mi masu]
It's my first time to watch/see it
初めて使います
[hajimete tsukai masu]
It's my first time to use it
これ（を）初めて作ります
[kore (o) hajimete tsukuri masu]
It's my first time to make this
----------------------------------------------------
初めて食べました
[hajimete tabe mashita]
It was my first time to eat it
初めて飲みました
[hajimete nomi mashita]
It was my first time to drink it
初めて見ました
[hajimete mi mashita]
It was my first time to watch/see it
初めて行きました
[hajimete iki mashita]
It was my first time to go (there)
初めて作りました
[hajimete tsukuri mashita]
It was my first time to make it
