When to start playing positional

Hi, I am a tactical player that only 1.e4 exclusively. I am horrible at the positional chess. Anyone got any ideas when and how I can start playing 1.d4 or 1.c4 (any positional games)and turn to positional chess. I am rated around mid-1500s right now (Standard). 

By when, I mean at what rating is it a good idea to turn to more positional chess?

Any rating, and the opening is irrelevant.

Good attackers are positional geniuses.

Quarki ...you have to learn sometime...

Positional chess refers to the position of your peices. Putting them on the most active squares possible even though you aren't neccesarily attacking anything. Example: Rooks on a1 h1 are less active than if you move them toward the center or onto an open file... knights developed to a3 or h3 are usually inferior to c3 f3. Slowly inching ur pawns up the board gaining space for your army ect.

What?

Positional vs tactical is a false dichotomy.  1.e4 vs 1.d4 is similarly not black and white.  Both opening moves can lead to extremely positional or tactical games and all games contain elements of both (unless you play by calculating literally billions of moves, per move, as computer do and davidegpc likes to troll people about).

So it's a bit like asking when is it a good idea to incorporate any basic skill... the answer is you already do (even if just at an elementry level) and it's never a bad idea to improve in an area.

That said, beyond a few basics, what you should focus on mostly is reducing gross tactical oversights. 

Positional basics include general piece activity (rooks on open files, knights on outposts, don't open a position if you're not castled or less developed in that area, king should be kept safe until the endgame) and some pawn basics (passed pawns and pawn majorities can be strong, isolated and backward pawns can be targets, etc).  Take these positional things into consideration in your moves (as I'm sure you already do).

If you want to increase your positional understanding you'd want to learn all about pawn structures and all the basic endgames.

A positional style is one where you try to make slow, incremental improvements to your position, but the game is relatively balanced and "under control". It is lower risk. Then, at a certain point in the game, without making any "real" blunders your opponent finds that he is lost.

Waffle, you mentioned backward pawns, I've seen that come up a lot in many different articles and chess mentor lessons but I still havn't been able to figure out what it means exactly. I assume its similar to a weak pawn? but what makes a pawn backward as opposed to just weak? Or are the 2 terms interchangeable?

a backward pawn is a pawn that doesn't have a pawn supporting it and cannot be advanced.

A weak pawn is a pawn that you have trouble defending.

Being good tactically means knowing what to do when there is something to do.

Being good positionally means knowing what to do when there is nothing to do.

1.e4 is a positional move.  It helps control the center, helps give mobility to the biship and queen.

1.d4 is a positional move, for the same reasons.

You'll notice that essentially nobody opens with 1.h4 or 1.a4.  That's because those are not very good moves. 

White normally develops their knights to c3 and f3, not a3 and h3.  Why?  Because those are not very good positions.  Knights are stronger near the center than off on the edge of the board.

Everyone plays positional chess at one level of another.

Early in the game, all your moves are made for positional reasons.  You don't have any tactics available on move 1.

"Strategy without tactics is the slowest route to victory. Tactics without strategy is the noise before defeat." - Sun Tzu

.