Hi and welcome for the marine forum.
You have come along way and it would be a shame for you to back off and turn to freshwater when deep down inside you have your heart set on salt. This is what i would do and always have done in the past.
FIll the tank 2/3 with RO water and add the salt to the correct SG levels (1.022 - 1.026) allow the tank temperature to reach optimum lvels and check SG again. Fine tune it by adding removing water to reach the correct SG level you are comfortable with.
Now add the livesand, this will create a dust storm but if you use a small spnge filter it will clear overnight usually.
Purchase the liverock once the tank has setttled (usually 24 hours). Make sure its Cured liverock and then place it in the tank as son as its possible from purchase. For a 46 gallon tank you will need 46lbs (or roughly 23kgs) of liverock. An initial purchase of 30lbs will be ok but remember the bioload will not be able to sustain much with so little liverock.
If you follow this procedure then there is no need to cycle the tank as it will already be cycled already with the sand and liverock. Fish (only 1 or 2 early on) can be added right away along with cleanup crew. Remember that the clean up crew are essential for a marine tank and their numbers in a reef should not be overloke.d Whilst you wont need a full compliment early on, you will eventually need a ratio of 1 cleanup crew per 1 gallon of tank (roughly) so get as many red leg hermits as possible and some astrea/.turbo snails.. also cerith snails are a good sand cleaning choice.
Make sure you get the good starter set of test kits... PH, Ammonia, Nitrite and Nitrate. Check water perameters daily for about a week and if the water remains stable then add more livestock. Remember though that you will want more liverock thanyou had previousl posted.
I hope this helps.