You can just look into the music itself. You can set the end of the intro with '/' (without quotations) which in your case would equal to the beginning of the looping part.
Keep in mind that it's pretty easy to mess up with an intro as if you time it incorrectly, your song easily desyncs and to make it worse, unlike (where it doesn't actually matter). Take a look at this example:
If you're wondering what ticks mean, but ticks is the unit of how long a note plays in NintSPC (the music engine we use). The explaination is a bit technically (so it doesn't really matter for a beginner like) but if you're curious, the smallest notes, one 64th note and one 64th triplet/one 96th note are 3 and 2 ticks long, respectively and each next note (32nd and 32nd triplet, respectively) are double as long as the previous note so their ticks also are doubled. In my example, channel 0 is 36 ticks too short (or e.g. three 16th too short). It's only really important with the use of hex commands (in which you have to look in AMK's readme, Hex Command Reference* anyway) or if you look into the song's stats (put in the folder, you guessed it, "stats") to see where the song (not the intro) ends, though.
*There is a small mistake at 16th triplet: The amount of ticks doesn't equal to $09 but rather to $08 given triplets are indivisble by three, not to mention that it's an odd value but the only possible odd value.
Keep in mind that it's pretty easy to mess up with an intro as if you time it incorrectly, your song easily desyncs and to make it worse, unlike (where it doesn't actually matter). Take a look at this example:
Code
#0 t38 @8 o2c+4c+8.d+8 ; 48 + 24 + 12 + 24 = 108 ticks / d+8d+8f8<c+16>c+16 #1 @3 o3f+16f16f16f16a+4a+8a+8 ; 12 + 12 + 12 + 12 + 48 + 24 + 24 = 144 ticks / c16c+16d+8c+16d+16
If you're wondering what ticks mean, but ticks is the unit of how long a note plays in NintSPC (the music engine we use). The explaination is a bit technically (so it doesn't really matter for a beginner like) but if you're curious, the smallest notes, one 64th note and one 64th triplet/one 96th note are 3 and 2 ticks long, respectively and each next note (32nd and 32nd triplet, respectively) are double as long as the previous note so their ticks also are doubled. In my example, channel 0 is 36 ticks too short (or e.g. three 16th too short). It's only really important with the use of hex commands (in which you have to look in AMK's readme, Hex Command Reference* anyway) or if you look into the song's stats (put in the folder, you guessed it, "stats") to see where the song (not the intro) ends, though.
*There is a small mistake at 16th triplet: The amount of ticks doesn't equal to $09 but rather to $08 given triplets are indivisble by three, not to mention that it's an odd value but the only possible odd value.