when you see tablature , there is generally no indication to the no. of strums or the amount of time for which to play the chord. Sometimes ou may have the position when to change the chord , but generally you'll have to listen to the song first . without listening to the sng you cannot even dream of playing it. the no. of strums on a chord depends on the rhythm. you must cathch the rhythm of the actual song. listen closely and check out when the chord changes. chord changes can be easily noticed. just listen to it and then play .
Guitar tablature like the one you posted cannot help you in anyways with the timing. you will have to listen to the song and deciode when to change the chord
Now I lay me down to sleep ,
Pray the lord my soul to keep,
If i die before i wake ,
Pray the lord my soul to take