I think there's only one type of bolivian ram - Mikrogeophagus altispinosus. I would keep a group of 6 or so in yours, I think they are quite hard to sex so not sure about ratios. I haven't kept them, but I would love to as they have very intelligent faces that tried to seduce me at the LFS. I think visiting a LFS and seeing which call out to you, and which seem the most healthy is the best way to choose (once you know their water parameters).
I think for dwarf cichlids you might need more structure in the tank to make a larger number of them happy - apistos are territorial, and they like to have "fences" to define their territory. Without "fences", they just constantly fight over who owns what, because there isn't an obvious way to define it. The only other options is to add so many that none of them can be territorial, but then it's like running a Mbuna tank with a high bioload and you couldn't keep many other fish. Much easier to add fences
Your tank is currently really one big territory. When the plants grow in this will change a bit, but it will need a lot more growth. For example, your sand is quite flat throughout the whole tank, and there isn't any large driftwood or piles of rocks or dried leaves to break it up, and particularly there aren't any 'caves' or cave-like structures for them to hide or claim. This isn't an aesthetics thing, your tank looks very nice, but just isn't ideal for a group of dwarf cichlids yet. You can still keep a small number, like 1 male with 2 female apistos, this is advice for if you want a few more, and/or want them to breed (where they get more aggressive).
You don't need leaf litter, but it's a really easy way to create this 'structure' and caves with almost no effort, and you get great natural behaviour because in the wild, apistos basically live in waters filled with leaf litter and twigs. 'Botanicals', which are just dried tropical seedpods and leaves are a more aesthetically interesting version of leaves, and people have a lot of success with apistogramma and these botanicals, are they like to use seedpods to breed in. You can also use ceramic plant pots, cut coconut halves and plastic tubes.
Below are some examples of tanks that show great structure for a nice community of dwarf cichlids.
<Tom's Poco Pozo> - I linked to a later page where you can see the way his apistos interact with the wood and have a cave. You can see that in a way your tanks aren't too similar, and a few wood adjustments so it's more set in the sand would make it work out great. If you haven't seen it, this is one of my favourite journals on the site and every page is great.
If you don't want too much hardscape,
<Giant tank for Killis>, is an amazing journal, with the plants dominating. The plants create lots of areas of shade and places to hide easily, where fish could have their own territory and not see another fish 30cm away from them in the grass. So you could just wait for your plants to get very bushy like this, and plant more as needed, and that would be great. Dwarf cichlids do like an area of sand though, a full carpet is beautiful but it would be better to keep an area of sand for them (which I would break up with some wood or rocks so they can share it without feeling too exposed).
Another example is
<Fifty Shades of Green>, which is completely massive but still has the same principles - there is a lot of hardscape, and with the plants it creates variation in height as well as lots of caves. There are also separate sandy areas. You could keep loads of dwarves in a tank like this and they'd be very happy. While apistos are bottom-dwellers, they will swim about, around, in & out of all hardscape and plants, no matter the height, so a variation in height is another good way to make territory.
Finally
<I wanted to show you my tank>, which as an example of a small tank for apistos with structure coming entirely from plants and dried leaves. I couldn't keep more than 2 adult apistos in this tank because of the size, (60L), but all the apistos I've kept in here seem very happy and they bred. For a while my apistos were harrassing my otos and kuhlis when the female had babies, and I solved this by planting more heavily, and by adding piles of leaf litter where any creatures could hide and live and eat without harrassment, and this in turn also made my apistos more relaxed. They bred in a long thin seedpod, which was very charming. I also separated the sand area a bit with some low grasses, so there isn't too much aggression there. In this tank, the leaves are mostly hidden behind and between plants, so they aren't even that obvious and I don't think make the tank look ugly. By hiding some of the gaps between plants, they actually make the tank look more lush, while also being useful. If I had a bigger tank, with the same lushness of plants and leaf litter, I could keep a lot of apistos without issues.
So I think you can def keep them, but you should wait a few months for your plants to grow, and maybe add some more plants and do some small changes to make it perfect for them. In return they will be very funny and you will fall in love with them, and then you will do even more to change the tank to make them more happy, and start evangelising everywhere about them like me lol